Man, awesome games coming out lately. I've been stuck on Oblivion myself as well. I've talked alllll about it over on JPM, lol, but suffice it to say, it's awesome.
Talk about 3-D lighting... I catch myself just stopping and staring sometimes at things the graphics does. Like, there's this one spot, I think it's like right inside the door to a Mages' guild, you enter the door, and there are windows in the door, right... Well, there's kind of a wall right in front of you with stairs on either side leading up to a slightly elevated first level. Anyway, on that wall right in front of you, there's some kind of metal plate that reflects light... I go back and forth, and I swear light looks better reflecting off that than in real life.
I wish I could describe it better, but you'd really have to play it to see... And play it on high settings like I do probably as well. >.>
Anyway, if the graphics (and sound) was all it was, it wouldn't be "great", but it's not. Gameplay rocks too... eh, if you're really interested, just search 'oblivion review' on google and read what they have to say. They do it well and it's all written out.
Of course, if you're really interested, you'd have done that already... that is, if you don't have it already.