Oblivion is a good game but if you want your moneys worth, be sure you get the game of the year edition.
Once you start you will have to create your character, which isn't too complicated but can be a bit long if you want your character to look perfect. All you're really doing is just naming your character, choosing the characters race, and editing the characters face but that's all thats really necessary anyways since the game is in first person view. When you finish with your character, you will then have to listen to some guy in the cell across from you talk about what suppose to happen to you if you stay in the cell but doesn't happen since the emperor comes to get you out anyways. He doesn't explain too much about why he's there though except that he saw you in a dream and that you suppose to be the hero who closes the Gates of Oblivion. Eventually he and some guards will escort you out of prison through the sewers and on the way will be taught the basics of the game thanks to Oblivion's tutorial. Eventually as you go through the tutorial, the emperor will ask you what stars you were born under. Picking the stars that you were born under gives you a special ability depending on the stars that you pick. Then near the end of the tutorial, you'll be asked what class you are which will decide all your major abilities like acrobatics and strength. Or you can create your own class which will let you choose the name of the class and what your major abilities will be. Then you can finely explore the world of Oblivion.
Oblivion delivers a huge world with almost non-stop gameplay where you can almost do anything from making friends and buying houses to killing others and pickpocketing innocents. It's graphics are like most next-gen games and not to mention quite colorful as well. But what the game of the year edition offers really pushes the length of the game that almost no one can complete it 100%. Not only does the game of the year edition offer a lot of updates but it also gives you the Nights of the Nine and Shivering Isles expansion packs. In the Nights of the Nine expansion pack, your given a whole new quest that has you discover the importance of the gods you worship and what they have done to become a god. And in the Shivering Isles expansion pack, your given a whole new world to discover and of course a new quest to keep you busy in it's two lands Mania and Dementia.
So if you're willing to go the extra mile then you should go with the game of the year edition. But if you're not then you'll still be kept busy with the almost endless amount of things you can do in the original version. Either way... You'll be happy.