A little noisy, but does a great job.
Does a great job at improving air quality in small to medium size rooms.  Notable difference in the air.  Will likely purchase a second one soon.<br /><br />Only complaint (and reason for loss of 1 star) is the mechanical whirring this produces.  It is annoying at first, until it settles in as white noise when you're near it.
Rating: 4 stars