Product review (4 stars): Useful and Easy-to-Use Data Logger.
I'm impressed with this little data logger.  I've used it to confirm cooling and defrost cycles in my fridge/freezer, to figure out a humidifier problem with my heat exchanger, and check the temperatures in my little wine cellar.  I also had a look at how our home's termperatures climb in the morning and fall in the evening, which helped me to properly set up our thermostat.  The display is very easy to read and the one-button control works well to start logging data.

I love that the temperature and humidity sensors are external.  This allows me to place the sensors inside a cavity and still read the display while it's sampling data.

The Windows-based software that I had to download from their site works well.  It seems to have everything I need, including a graph of the samples data that includes just temperature, just humidity, or both.

I didn't give it five stars because the software could use some cleaning up.  It's clearly written by a Chinese dude, so there are a few spelling mistakes.  But more importantly, there are a few oddities.  When I exported data to excel, the data is in text form rather than number form.  So in excel, when I tried to create a chart, excel was not happy.  I had to play around and convert various cells to the proper formats.  Also, the only way I can figure out to clear old data and start a new sample is to change a value in the parameter setup.  There is probably a more direct way, but I haven't found it.

If the software UI were cleaned up a little bit, I'd give this product a 5 star rating.