Agreed! I enjoyed NMC's texture pack for Fallout 3; really enhanced the game. But....
It looks good already. It's overall smooth for me. I have it installed on an SSD and have some good GPU horsepower, but it worked fine with a single 5870 enabled too (at lower settings), and I've had no multi-GPU issues after testing with several configurations and settings.
I've run into a few minor problems in the game, but no "game breakers." Some of the terrain and features are not polished (for example, in some places, rocks hover over the terrain slightly rather than meeting it seamlessly).
The biggest annoyance to me: the invisible barriers blocking the player from going places you would otherwise be able to go; e.g., bluffs/hills/rocks you know you could climb over, but the game doesn't let you. That combined with the layout of various terrain features and objects really works to route the player where the game wants you to go, which to me flies in the face of the non-linear, open-to-exploration quality of the game that makes Fallout great.