I feel like Akira Toriyama just starts each manga by asking femself, "What type of story can I create that'll maximize my ability to draw rocky wastelands?" This story's pretty simple, but that doesn't mean that it's necessarily bad. It's adequate, and the fight scenes are on the superhuman level that you'd expect from this author. My favorite part of the manga was Donko and the wiley ways that fe played both sides and tried to make a quick buck. It's also interesting how feir ridiculous speed was never given an explanation, but it's probably better that way. Not everything needs to be explained.
I didn't care for the black-and-white notion of "good people" and "bad people," or the way that somebody's badness could be removed from fem. I also didn't care for the final joke that the manga ended on--it wasn't very funny and it also didn't make a whole lotta sense within the larger trajectory. I assume the author just didn't know how else to wrap things up, so included a weak full-circle thing.