Most of the reviews I hear are mixed. People either love them or hate them.
I played with one for a bit, and I could see it being useful for like one-off concerts and events, but not really for theatre, where you lay stuff down once and maybe re-tape it a few times.
I just don't think it's worth the upfront cost. I'd rather pay an PA with the money I spend on one to do it and be able to do other things as well.