The arms don't fit universally across the resistance figures. Each body is marked with a letter, which has a few different weapon options that will snap together. I had to do some work with my hobby knife to create some figures outside of these options. They look decent, but there are definitely a few weapons that won't work with some of the bodies.
The human sculpts are a bit soft, which is a little sad based on how much the box costs. I know it's largely due to the licensing being built into the pricing. I hope the single figure boosters (t-1000, Arnie) will have nicer quality. I haven't seen any available locally yet however.