Oblivion combines an incredible amount of content with mouth-watering graphics and an honestly touching plot.
Well, for one thing, Bethesda actually LISTENED to our feedback from Morrowind. Since Cyrodiil is even bigger than Vvardenfell was, it was vital that the players be given new tools to ensure that they didn't get lost. Between the Fast Travel option and the fantastic map and compass, that's not a problem in Oblivion.
The other problem with Morrowind was that it basically just dropped you off from the boat and said, "There you go, have fun!" Which left some people wondering where the plot was. Again, not a problem in Oblivion. You start on the plot, and you'll always know where the plot is, but once you've escaped from the opening dungeon you are free to follow or ignore it however you wish.
The game has a stupid huge amount of content, just as an Elder Scrolls game should. By the time I finished the main plotline I had completed over 100 quests and I know that there are tons more out there that I missed.
The graphics? Well, I am fortunate enough to have a good computer with a great video card, so I was able to keep the detail setting fairly high, and at several points while playing I just had to stop and look around at how pretty everything was. You've seen the screenshots, you know the game is gorgeous.
The weakest part of the game to me was the Plane of Oblivion itself, which got kind of monotonous after a while, but other than that, the game is just pure RPG candy. And such big portions!