Product review (4 stars): Nice price, great accuracy, Display relies on ambient light for good visibility
VERY SENSITIVE
This is a nice little device and is very sensitive, to any variation in temperature and humidity. In fact moving it from one spot to the other, it will show the variation.  Picking up and holding it will show variation.
We tested it against our other devices and to be honest, I would rely on this gauges information over the other.

HIGHS AND LOWS RECORDED
I like the fact that it records high and low of both temperature and humidity, so you can see if your HVAC system is up to snuff.  I have a whole house humidifier that this device helps me know if it is working well or not.  In the winter it can get really dry and this gauge reminded me to turn the system on for the season.

CANT SWITCH MEASUREMENTS, TO SHOW TEMP LARGER
What I thought was odd for a digital device was that you could not switch which measurement was emphasized.  This gauge shows Humidity in a larger font than Temperature.  I thought it would be nice to be able to swap which one was larger.

NEVER USED THE ALARMS
Ive never used the alarms, as I did not have a reason to. Did not want to accidentally have them go off when I was not here and drive my cats nuts just to test them.

MAGNETS ARE NICE AND STRONG
The magnets on the back are powerful and easily hold on a textured refrigerator, so a nice flat metal surface would be even better (tried it on my dishwasher and it snapped right to it).  The magnet on the bottom also holds it to the plastic base.

DISPLAY VISIBILITY
Regarding visibility of the display, it is not as bright as the photos unless your room is well lit. It relies on ambient light for visibility and does not have a backlight.

USES REGULAR BATTERIES
This uses 2 AAA batteries so you can easily get them.
Put these batteries in, in November and still going strong 4 months later.  But I would expect that, these should last at least a year with this type of low power display.