Basically there are two camps:
pro: I have one, it was cheap and has not broken
con: a straight copy of an AR15 lower does not translate well into plastic and may break, some plum crazy lowers, which are the same mold, broke
pro rebuttal: the picture of a plum crazy that broke looks like it was mashed in a vice, NFA uses different plastic than plum crazy and none have been reported broken.
I have one sitting at a gunshop to try out, but personally I think a forged lower is so cheap right now I would not bother with one except for it being for shits and giggles for the site, but who knows