I'm not going to repeat what was said in the previous 3 reviews, but I will say that all of the reviews were very accurate.
This unit is efficient and quiet. The confirmation beep is a bit loud as mentioned in another review, but not too bad.
The heater puts out a good deal of heat. I put it to test in my garage. The garage is 24x24 with 10 feet ceilings, and lightly insulated. This unit probably wasn't meant to heat such a large area, but it still did a good job. On an evening where the temperature was 40F outside and the garage temp was 61F, after running the heater for one hour on the lowest setting, the garage heated up 6 degrees to 67F. I was able to sit in the garage enjoying a nice cigar without a coat on. We'll see how it performs during one of our bitter cold Chicago winters, but I expect it will be fine as long as I sit near the heater--which is how I plan to use it. I also plan to use it in my basement office. I'm sure it won't have any trouble warming that room (8x12).
The unit is very quiet at it's lowest fan setting--you can hear it, but just barely. Running it on the high fan setting naturally generates more noise, but even at the high setting the fan noise is much less than a typical bathroom fan and very reasonable.
The heater is built quite well and doesn't take up much space.
I'm very pleased with this purchase--it was worth every penny.