I've always been very skeptical of air purifiers and that I would really benefit from one...until I bought this little guy.  I live in a small one bedroom apartment (built around 1900-1920) and one day discovered black mold in my bathroom (not the point of this story), but to make a long story short, as a result of this mold insanity I ended up with air purifier.  Oh and around this time I had also gotten a cat which I realized made my allergies worse.  So with black mold and pet dander floating everywhere I had been feeling your normal allergies.  Then this little thing came along.  The first day I flipped the switch on the little guy I began to notice a difference - a huge difference, like I wasn't waking up with a scratchy throat and itchy eyes.  Since then I've had it running consistently.  I crank it up a bit more when I brush the cat to help get pet dander out of the air a little faster.  It takes very little maintance.  I wash the pre-filter whenever I see it getting dirty (every month or two??) and the HEPA-type filter has lasted 6 months thus far (running all day).  It's not too loud, it sounds like a typical fan.  The controls are very easy to use and the filters are very easy to get out/put in).