As far as I can tell the Nux does everything the Boss does (it's an RC-3 clone) and has pretty much identical specs. It's built solid, is totally reliable & works/sounds great too, however I've never A/B'd it with the RC-3 so I can't comment on differences (if any).
Here's a jam I recorded with it using just the looper (onboard drums, except for the fills which I added later..). This one was mastered but I've got a zillion raw practice video's and random improv jam's I've recorded with it up on my youtube channel (link in my sig).