Product review (4 stars): Seems to be fairly accurate
I bought this to add to my Honeywell TM005X Wireless Thermo-Hygrometer which can monitor up to 3 remote stations.

I had purchased a wireless therm-hygro unit from WalMart earlier this year, but wasn't impressed with the quality and their accuracy.  Took them back and ordered the TM005X with this additional remote.  IMHO, the Honeywell units are much better.

I have the base station and 2 remotes.  I've installed new foam insulation and an unvented roof in my new remodel.  I use them to monitor temp and humidity in my basement, main floor and attic.

You line them up in the same room and the temps are all within 1 to 1.5 degs and the RH are within 2% to 3% of each other.  I haven't calibrated the units yet, but so far I'd consider them a pretty good value.