Weak RPG, rather an action/adventure/shooter game. A dumbed down Elder Scrolls aiming at the largest audience's wallet.
IMPORTANT: The level scaling, meaning that the whole world levels up with you, is a terrible blow on the head of the Elder Scrolls series. It dumbs down the game, removes all excitement and purpose from the game-play, and pushes Oblivion away from the Role-Playing class.
It's clear that this game has been made with a sole purpose in mind : to reach an audience larger than the Role-Playing community. I guess it is a success for the company, finding so few reviews from RPGists, mostly angry and stunned with disappointment. Rare bad scores lost among a crowd of praising reviews from less demanding gamers, easily dazed by the flashy but weak and boring Oblivion. Personally, during the many hours I invested in this game, I spent most of my time time trying to figure out why I was feeling so bored, rather than enjoying it .