I want to preface this by saying that I've not had a lot of non-GW minis prior to picking up Malifaux and I've only painted 3 Malifaux minis (all Rotten Belles) so far, and I'm awful at the painting aspect of the hobby...
With that said, I feel like these models are excellent in that they are all very unique, styled and fun minis. I do feel like they are not quite as detailed as most GW minis, but that's not necessarily a bad thing.
As far as prepping them I didn't have any issues. There were a few minor mold lines, and most of the models I've picked up require at most attaching one limb so far.