I've been in love with this game also, the more I explore and the further I delve, the more I just want to continue playing. I've racked up exactly 17 hours believe it or not since getting it for Christmas, and I'm yet to fully complete a main quest yet. I've done a hell of a lot of wandering and I'm currently at Level 5 I think for my character and I've leaned more towards choosing perks related to speech, bartering and science etc.
I'm trying to play the game out in a friendly manner and attempting to gain good karma where possible by running errands for some people. However if I see a big opportunity to benefit myself, I'll do so and this was demonstrated when instead of just doing business with a scavenger by a dockside, I shot him in the back of the head and watched him flop face first into the river before proceeding to steal him of everything, including his wet clothes.
That is the beauty of the game, one moment I want to be as helpful and talkative to people, then the next nothing is going through my head but every man for himself, dog eat dog (literally sometimes).
Smashing game and fast becoming my favourite of 2008.