Product review (5 stars): More useful than I originally thought, my reservations on purchase unwarranted.
This does exactly what it says it does, and it does it well. Granted, I live in an 800 sq ft. apartment so I'm not really pushing it too hard in terms of distance, but it's really nice to have the main unit hanging next to my thermostat so that I can turn my thermostat to a temperature based upon the hottest or coldest part of my apartment. I currently monitor the living area (main unit), kitchen (small unit w/ display), bedroom (small unit w/ display) and the patio (small unit w/o display).

In my situation, the battery life seems to be very legit, rechargeable 2100mah batteries have lasted a few months with no signs of dimming or problems in that area. I would expect them to last all year at this rate.

It makes you wish it could log this stuff over time so you could see trends, and it makes you wish it could be hooked up directly to your thermostat.