I'm 8 hours in and it seems to me like something's missing from this game. And I love Oblivion to this day.
There's way too much time spent underground following train tracks, and after emerging there are a LOT of places where you are further funneled along by virtue of collapsed buildings and so on. This is not only in opposition to the very idea of an open-world game, it's also very frustrating as you spend too much time backtracking. At this point it feels the same as it would if you had to get to each of the big towns in Oblivion by navigating one of the underground ruins. Maybe it opens up further in the future (and allows you to stay above ground, out of the bland, confusing tunnels).
My biggest complaint by far though is the gun combat. Earlier I was standing 4 feet away from a guy, shot 14 bullets at his chest and missed each time. I know this is based on skill, but a certain base skill should be assumed, let's say...what my mother could do in real life? Then there's the fact that I can shoot a guy six times in the head with VATS to little effect. I mean...even GoldenEye had headshots. And with the inaccuracy already present in this games' aiming, especially further than 15 feet or so away, I daresay that including headshots wouldn't unbalance it. To say these issues are frustrating me is an understatement.