I disagree with the previous 2 comments.
I was a HUGE fan of the other 2 Fallout games (not counting Tactics or BoS), and only mildly amused by Oblivion. I think Bethesda have done a great job. There is a bunch of humour in the game, and the graphics are great.
Reading the other comments i feel like maybe i was playing a different game =P I do agree that the main storyline is short, but there a HUGE number of side quests, and many different ways to do things.. You could spend (literally) hours exploring just the ruins of DC alone.
The sneak skill is one of the most useful.
The ability to pause at any time to apply a stimpack (health regen) makes combat relativley trivial, but overall a fantastic game which i have loved playing and look forward to any expansion.
Only thing that stops me from giving it 5 stars is the crashing issues which i hope will be resolved soon in a patch.