Product review (3 stars): They are ok, but they could've been better.
I had 2 of these monitors for a month now. They are not super accurate when compared to each other, there's at least 1F difference in indoor temperature and 3% difference in humidity when placed next to each other. I placed one of them on a fridge (using its magnet) inside my attached garage (temperature gets there up to 109F - Phoenix, AZ) and the monitor fell off the magnet in exactly 3 weeks. I guess the glue deteriorated in 100+ degrees temps pretty quickly.

Since I only care about the temps, these units are ok for my purposes and 1+/- degree doesn't make much of a difference to me. They are good looking gadgets and will do for now, but my personal satisfaction level is not more than 3 stars. I'm in need of a couple of more monitors, I may buy the same ones, but I'll shop around again before I do.