As for me, I use (planning to) it exaltly for what it was designed for - the remote IO, however only a few features - discrete input and output (for now, may be some one wire temperature and humidity sensors later). I have esp-07 module and some sort of control software https://github.com/awareness-project/awareness. Your product make it possible to connect them together very easy. Just have tested blinking internal blue led of esp module, but now I see it works good, and going to use solution in house automation tasks
The only thing I have noticed, that I can't properly communicate to module via windows telnet and wasn't able to finetune putty. Module was able to understand what I was typing 1 time of 10 attempts. But then I tried telnet running under ubuntu virtual machine and all works like a charm. So this is not actually a problem for me now.