Product review (3 stars): Good value for the price, didn't meet accuracy specs out of the box.
I was provided a free model to review, but will try to leave as unbiased a review as possible.  Amazon policy requires that reviewers disclose when they are provided free samples for review which was probably the case with many of the early reviews for this product.

It came with a handy carrying pouch.  I was surprised to see two open holes in the front of the meter, thinking that would easily allow water and junk to get inside, then it occurred to me those are probably to allow free air flow to the temperature and humidity sensors.  It's probably a good idea to use the pouch for carrying it in your pocket or a bag to keep lint and junk out.
Fit and finish isn't great, the gap in the seam around the front and back half of the meter case wasn't very even, but at this price point I can't knock it too much for that.

The temperature read about 3 deg F high at room temperature.  I checked it after leaving it for a few hours, sitting in close vicinity with the reference device which was a calibrated laboratory thermocouple instrument accurate to +/- .5 deg I tried a couple of reference thermocouples, with the same result.  It can be calibrated but Its worth noting that it fell outside of the stated +/- 2 deg accuracy spec, out of the box.

Humidity varied quite a bit as much as +18% compared to a calibrated portable Omega meter with +/-5% accuracy.
The picture shows the WM-3 and a Omega Temp and Humidity meter after they had been sitting together in my garage for a few hours.  The WM-3 screen looks bad because I hadn't taken the protective plastic off yet.

 I didn't have convenient access to an anemometer so I held it as far out my car window as I could and drove slowly up the street and its wind speed tracked the speedometer pretty well up to 35 mph.  The manual warns against doing this too much because it will wear out the fan bearings.

At one point I put it in the freezer and came back half an hour later and powered it up, the screen backlight flickered a bit and read -14.5 deg F, my portable reference meter read close to 8 deg (rated for +/-2% accuracy from 40F to 90F so it was outside it's calibrated range).  After a minute I opened the freezer again and it said "Lo" instead of indicating temperature.  If you are hoping to use this to monitor conditions on your summit of Everest you'll want to up your budget a bit, this thing isn't that rugged and, in fairness, doesn't claim to be, It's only spec'd to go down to 14 F.

The hold function worked but I never saw the word HOLD on the screen as the manual stated it should say.

For the thirty something dollars price range it's a cool little gadget, providing temperature, humidity and wind speed along with some handy, min, max and hold functions and display options but I have to knock some points of for it not meeting stated accuracy specs out of the box and a somewhat cheap feel.