Great game!
Whats great about it is:
the music: amazing soundtrack and in-game sound effects
graphics: very immersive - you really feel like your alone in the "wasteland".
weapons: a very fun and large assortment of weapons
levelling up: heaps and heaps of fun ways to improve your characters skills and "perks".
fun characters: there are so many weird and wonderful characters to meet and interact with...
moral choices: the game makes you feel bad when you're bad and good when you're good!!!
Another thing that really makes the player feel involved is the fact that the world seems to revolve around YOU. The choices you make can make a huge difference in the game and the radio often makes mention of what you are up to which can be quite amusing/entertaining.