Product review (1 stars): Good for one day, then...
Out of the box it worked.  For about one day.  Then it started giving incorrect readings, measuring the temperature a full 10 degrees lower than it really was in the house.  It runs through batteries and makes a loud, frequent beeping sound as it drains a battery.  This noise is so loud that even though the unit was placed downstairs it woke my wife and me up in our upstairs bedroom at three AM.  Even when the batteries are fresh out of the box, the unit acts strangely, switching for no reason between Celcius and Fahrenheit and freezing on previous memory settings.  The ONLY way to get a current reading is to hit the rest button and wipe out all of the data.  Even then, of course, it gives inaccurate temperature readings and likely humidity readings as well.  That is, unless you really can get a winter nosebleed when it is 75% humidity in the house.  Save your money.  Buy ANYTHING else.