Product review (4 stars): Really good, and definitely worth buying, but there is one major physical design flaw...
Marvelous!  We've tried/tested several different devices for indoor-outdoor temperature & humidity (see my other reviews) and this one stands out among them for its features, especially ease of use, ease of viewing, and having the right info in the right place.

THE PLUSSES

It's easy to read from a distance; it properly puts temperature first, then humidity; includes a barometer-- and a graph of pressure for the past 24 hours, so you can see if weather is getting fairer or not; and has a Moon phase display which is great for those who enjoy stargazing.

You can also cycle the 24-hour graph through for indoor-outdoor temperature and humidity, too,

We got this one because it has humidity "calibration"-- you can alter the display +- a certain amount.  However, we've found both temp and humidity quite accurate.  That was gauged by comparing it to a set of regular thermometers and other gauges-- and to itself!  You put the sensor next to the device indoors and see if the indoor-outdoor readings match.

The backlit colors are great, too; giving one a feel for the outside temperature by color code.

One big plus-- this operates off both electricity and battery.  Best to leave it plugged in.  The cord is long enough to put it on a table.

A PRO AND A CON

Now, the display is BRIGHT!  That's great for seeing and reading it but, at night, the light is almost blindingly bright-- so much so that you'll think someone has left a light on in the room it's in!  OK, no problem, as the top button can be pressed to turn off the light, then in the morning, you can turn it on again.

A NEGATIVE

However, pressing that top button takes a fair amount of pressure and you have to hold it down for a couple of seconds to turn the display on more than momentarily.  This worked fine for us-- until this morning, when the kickstand broke off and the device slid off the table and crashed to the floor!  Turns out that the kickstand is attached to the back only with two tiny plastic pieces that are easily broken off!

It's a real shame as it means the unit can no longer be propped up on its own for viewing!  (We had a spare, inexpensive plastic mini-easel that works, though it looks poor aesthetically.)

The moral of this story is to use 2 hands to turn on the backlight-- one, to hold the unit and the other to press the top button.  Otherwise, the pressure is transmitted directly to the kickstand and it will eventually break off, as it did to us.

In any event, other than that, it is a good product and now occupies the central place in our corral of indoor-outdoor devices!