About as close as you can get to an endless RPG
Gameplay: One of the failing factors of Morrowind was the boring fighting system. You don't really do anything other than cast spells at the right time and mash your mouse button to attack. Shield is automatic, very few different moves (most of which are pretty pointless anyway, and even that could be taken away simply by clicking the "always best attack" option. Oblivion tries very hard to amend this mistake. Not saying that they failed, far from it. But it still could have been better. Basically, the differences are that you now control your shield/blocking which is extremely important in most battles. Also, when you get to a higher rank in your weapon skill (explained later) you get new "power moves". The skill system is what has been given the biggest overhaul. The skills have been blended together/cut from the game to make only 21 skills. Daggers, swords have been thrown into the category of blade, Axes, hammers are now blunt, etc etc. Also you only get 7 major skills that effect your level up whereas in morrowind you had 5 majors and 5 minors. This would make leveling up slower if not for the fact that you now increase skill levels much faster. Stealth players rejoice! It is now much, MUCH easier to increase your sneak skill. Finally, the magic system has been highly improved. Maybe it was just me, but in Morrowind, magic was incredibly hard to use in combat because of it's unreliability if you have a low skill level. Thats gone, spells always work in this game but they tend to be weaker. It's a good balance in my opinion. The one place that Oblivion lacks is that there are far less factions to choose from. In Morrowind you could do Fighters, Mages, thieves guild but also choose from Imperial legion, Temple people (forgot what they were called), one of the three great houses, and a bunch more that i can't remember right now. Instead of that, they decided to have less factions and more random quests from completely unimportant people. I personally liked the faction quests a lot more. This doesn't mean that the random quests are bad though, some are very in depth and detailed, making you choose which way to complete the quest, having twists and turns in their miniature storylines, it's really very well done. It's just that it doesn't feel as rewarding to beat the quest when you know that all that will happen is you get a little gold.
Graphics: Wow... really wow... they're demanding but if you have a good enough computer, the graphics are absolutely amazing. They have the best character models i think that i have ever seen. The only thing I don't like is that my favorite race (argonians) look way stupider than they did in morrowind. I got over it.
Sound: I literally will wait through the whole opening scene simply because I love listening to the music. It's really well done and always fits the mood perfectly. It also will actually help you in game since the music changes when enemies detect you. So even if you can't see the enemy, you know it's close by. Value: Are you kidding? It's Elder Scrolls! Easily 100-200 hours without even getting any of the thousands of player mods out there! You won't be putting this one down for a LOOOOOOOOOOOOOOOOOOONG time.