A terrific, immersive game that is hands-down the best RPG in current history.
I, personally, hated Morrowind. Just couldn't get into it, and it felt very static and unbelievable (in the bad way.) Oblivion changed all that. With all the dlc adding amazing new quests and great new bonuses to the game, it only got better from the beginning. All characters are fun to play as, no matter what class or race they are, and the many different options will keep people playing for years (Or until the next Elder Scrolls comes out; whichever comes first.)
Overall, I can only say that this has completely changed my ideas about games, and got me immersed in the RPG genre, and, I daresay, broke my addiction to Halo. (Though I fear it is steadily growing again.) I personally can say I've never played a game so open-ended and amazing.