Off the charts.
1. drink water from a toilet- gross but its a means of health replenishment.
2. make your own weapons- you can find blueprints to creating special weapons.
You have a choice of being good or being evil but each side has its consequences or rewards.
The one thing I don't like is that when you explore having a good lockpick level and science is a must. I always start off with melee and such because no one is gonna punk me.
Last it also has a little humor to it. For example I love using my sledgehammer to bash anything I see, and using V.A.T.S allows you to see it in slow motion, exploded body parts flying everywhere. I also think super mutants have funny reaction when bashing them with the hammer.
Overall this game is awesome, oh and one other con for me I don't know about everyone else... there is no flashlight just that dinky light from the pip boy. I want to be able to see everything and having that rinky dink light doesn't help at all. This game kind of makes you think "is this how we would be living also if our country got hit by a nuclear explosion".