I tried it recently, even paid for better plan.
In fact it's uncensored, didn't reach limit any time, but quality is shitty comparing to grok. It needs several attempts to generate proper human body, more complex prompt will almost each time generate something broken or not expected.
I would say flatai is nice if you have already prepared photo and you want to undress it (or remove censorship), but if you want to generate nice photo with just face as source (e.g. better outfit, better pose, better background or face details), grok is way better.
I will test flatai until my sub is over and after that I will look for something more like grok - I think better tool with censorship is better than worse tool without filtering.