Nobody seems to be writing anything on this area, so I might as well break the ice.
Yeah yeah I know. There are a bunch of reviews about it already, but whatever. This is going to be long and tedious, so hold onto your mugs of coffee, ladies and gentlemen.
So, Oblivion. Successor to Morrowind; unsurprisingly, it's a pretty cool game. You know, vast expanse of land, like ten cities, all sorts of monsters and weapons and skills. I mean, sounds great.
In the big picture, anyway. When you look at the details, that's where Oblivion has been crudely taped together, and, unfortunately for Bethesda, they were trying to build a monument. Bad combination.
But hey, instead of an incoherent ragefest, I'll cut things up so they're actually understandable.
Storyline! Well, the Elder Scrolls franchise has a lot of lore and backstory behind it. Except, well, you wouldn't be able to tell from Oblivion. All of the 'lore' is pretty much mentioned only in books (which you will have no inclination to read, due to nearly all of them beingcopy-pasted from Morrowind) and are mostly contradicted gamewise. Example, Cyrodiil (where Oblivion takes place) is supposed to be a tropical jungle. And yet it's a generic stock-fantasy European country in-game. Huh! Amazing! As for the actual plot of the game, it's your basic fantasy stuff. Blah blah blah, save and unite empire from super mean evil. An evil that apparent has no motive whatsoever but to be evil. OH WAIT HE'S THE DEMONIC KING OF DESTRUCTION AND CHAOS HE DOESN'T NEED A MOTIVE. Whoop de fuckin' do, Bethesda. So basically the entire main quest consists of fetching random baubles for the emperor's unloved and unlikable bastard son who needs constant reassurance that he's doing a good job despite that he does absolutely nothing throughout the entire game. Well, at least he has his own voice actor. Nice to money Bethesda's financial management is still top notch.
Leveling system. Big one. Okay, so the basic idea is really nice; keep the player constantly challenged by having enemies and gear always around his or her level. Problem is... well, it totally limits the freedom and danger aspect. In Morrowind, you had to watch yourself when you were out in the wild, otherwise you'd get gored sideways by heavily-armored cultists or claw-tastic Daedra. But in Oblivion, you can always count on the bad dudes packing whatever you're packing, always weak enough never to overpower you. Even the endgame bosses are watered down if you're still weak. Hell, the entire main quest can be completed at level one (despite that it recommends level two). Amazing, huh?
Also, the leveling system destroys the point of exploring. In Morrowind, who knows what the farthest reaches might hold? In Oblivion... you already know. Whatever is guaranteed by your level. Sad, huh?
Now, the combat. Supposedly upgraded from Morrowind. In a sense, it is; you can manually block, you can cast spells whenever you please, and you gain new... er... 'techniques' as you level weapon skills. Problem? Well, this is all grand... but it all boils down to the same. Power attack, block. Power attack, block. Chase after mage/archer. Power attack. And that, ladies and gentlemen, is the combat. Sure, you be sneaky if you want, but it all ends the same way. If the game was only an RPG, the combat system in itself wouldn't be so bad... problem, however, is that you're constantly fighting (as in, an action-RPG style) and the AI really, really brings it down to repetitive tactics. It doesn't help that you become godlike once you get the hang of Alchemy and Illusion. Just like in Morrowind. Some things never change.
The AI. What was it called? Radiant? Yeah, sure. Maybe because it radiates poor scripting. Enemies will stand unblocking as you attack, they will attack when you block, and when you begin using ranged attacks on them, as opposed to taking cover or blocking as they advance, they just run straight at you. Wow. Goldeneye 64 had better AI than this.
And the so-called 'schedules'. Supposedly all NPCs follow a realistic frame of day-to-day action, all with their variations. Well, surprise surprise, they don't. Bandits, necromancers, basic sword fodder and other unimportant NPCs stay up 24/7 except for a few special cases. All citizens wake up at 9:00AM. All shops open at 9:00AM. All shops close at 9:00PM. Between this time, guess what the NPCs do? That's right! Stand around staring at walls, walking around pointlessly, or talking about the same stuff that was talked about yesterday. Shop vendors will stand behind their counters all day, in worse cases all night too. Oh, right. Sometimes they talk about quests you complete. So it looks like Bethesda sort of blackmails you into doing quests to prevent yourself from being annoyed to death by "lulz mudcrapz".
The guards. Utter stupidity. I can stealth kill someone, crouch over their body, and a guard will walk up, check for a pulse, say "Huh, still warm, there's a murderer about" and walk away. Even better! Wear the assassin gear of the bad dude guild, and ask for a certain person. As opposed to saying "What, going to kill him? Die, assassin!" The guards just tell you where said person is. Without noticing your clothes. What. Seriously, 'Radiant' AI? The only thing fucking radiant is Bethesda's opinion of itself. "Gee golly wiz, I can copy and paste the same shitty script to like a thousand NPCs. I'm clearly a script wizard!" Christ. And even better! Break into someone's house, and wake them up. They'll say "Oh good day" and go back to sleep. Because whenever a psycho breaks into my house, naturally the first thing I'm going to do is say hello and ask him to close the door on the way out, and immediately go back to sleep.
Ah, sound. Main composer was Jeremy Soule. Did some others sountracks which were pretty good, but Oblivion seems to be rather mediocre in comparison. There are no stirring pieces, just generic strains of unemotional stuff. Battle music doesn't get you pumped. Town and explore music is repetitive. Better to play with the music off.
And the voices. Same guys from Morrowind, except for those elf weirdos. So basically you have seven talentless actors doing like 300 lines each, all during the same recording session. What do you get? Shit, obviously. No emotion, no conviction. Just lines read off of paper.
That leads to the new conversation system. You get an NPC's ugly mug shoved in your face whenever you are forced to talk to them, and they generally will make no gestures or show little emotion as they speak, aside from 'rarar angry' or 'lolo happy'. I'd rather read text than have mottled dermatology abominations thrown at me, thanks. Doesn't help that they just stare... and stare... until you leave.
Right, back to meaningful stuff. The skills. See, in the beginning, it really doesn't matter what you are. Why? Your initial skills start off at 25, while everything else is at 5 or 10. HOWEVER, your unfavored skills are not penalized at all, not even by their attributes (a la Morrowind). Feel remorse for being a lame ass wizard? Go ahead, pick up an axe, slap around a few sheep and whores, and shazam! Instant barbarian asskicker.
Which leads to guilds. All of them revolve around only you. There are no 'Radiant' guildmembers who do stuff, only you. Other members don't level up unless you make them via scripting. The guilds don't conflict at all. At all. And within six or so quests, you make it to the top no problem. Seriously, what? A level one can get to the top of every guild? What gives?
Okay okay. The compass and instant travel. Everyone hates them. Why? It strips the game of realism. "Here's a horse, go here." Why? I can zap myself there, silly fool! And thus the lameness of fast travel. Why bother having a decent looking landscape when you can just fly through it? Oh, that's right; there's nothing worthwhile in said landscape. Even if you run into a settlement, chances are they have nothing of worth to offer you; just bland NPCs thrown into the wild for you to find and think "omg depth" as opposed to "omg laziness".
And stolen goods, let's take stolen goods. How would someone know this rock I have is stolen? I expertly procured it from the house of a mad scientist a mere five minutes ago! Yet the local merchant refuses to barter. Okay, so merchants can magically tell when something's been stolen?
Let's look at some other stuff. Take horses. They cost about, say, 500-2000 gold. Makes having sneak kind of nice. Problem? Why bother with buying a horse when you can just do the Dark Brotherhood for a free invincible one? Yeah, that's right. A free God damned invincible horse.
Whoa, hold up. Doesn't Bethesda have a ten-dollar horse armor DLC? Then why do they have an invincible horse?
And that, ladies and gentlemen, is exactly what I have been bitching about for the past many words; inconsistency in detail.
Okay wait wait hold up. Maybe I'm conveying the wrong idea here. Okay sure, Oblivion is no masterpiece, not by a long shot. However, it isn't a bad game. Hard to believe from what I say, but there is one massive factor in the enjoyment of Oblivion.
Yes, mods. Improve the graphics, improve the AI, crank up the difficulty, heighten the stakes, better the quests. Mods can repair just about ever flaw in Oblivion there is. They can make leveling more important and interesting, combat more harrowing, guards more intelligent and suspicious... it's great.
So. Is it worth the buy? If you LOVE Elder Scrolls and have a good computer, sure. If you're not all of the above, don't bother.
Moral: Instead of playing this game, throw a massive block party. When everyone's drunk, give everyone swords and scream "EN GUARDE!"
Summary: like western RPGs and fantasy, go ahead. Otherwise, give it a rent.