I just have the demo, but I love being a theif. Break into a shopkeeper's house at night, steal their stuff, sell back what you don't want in the morning, repeat the next night. Hehe
My wife plays a thief character exclusively. She seems to really like how thieving is handled in Arcanum as well. If you're stealing at night, you may want to try the Dark Sighted Background. If you break all the lights in an area when a guard isn't around, that'll give you some nice advantages over them when it gets dark.
Yeah, I tried braking the lights but it wouldn't let me in the demo. Also, when I summon a creature i can only see the shadow below it and it won't do anything for me.