It makes a 15 x 15 small office very toasty with reasonably quiet air blow.  Used it during the day --- turn it on around 8:45am and it will run continuously for about four hours to
reach 72F, then it will auto-start once in a while. Used daily
for a month now, and electricity bill show minor change.  Also bought the DuraFlame Levingston at the same time, their effectiveness is similar, although DuraFlame is slightly louder (it's fun runs a couple minutes after the it is turned off to push out residual heat from the unit) but significantly better in the exterior built quality.   Of course DuraFlame is more expensive than Dr. Heater.  Both cool to the touch on the top so we often use them as side tables.