It actually works, but for a smaller space

I have bad allergies, and my Oreck air purifier was not working at all. After my research I found the Alen 350 and decided to give it a try in my 150 sq ft bedroom.

Weight : The unit is light and easy to move places. It is also sturdy, so it won't tip over.

Noise :

Lowest Setting : Very quiet, you won't hear very much
Setting 2 : This setting is about as loud as a fan, so it isn't very annoying at all.
Setting 3 & 4 : These two settings are very loud and will be a nuisance when you are trying to listen to something else. On a side note, these settings are excellent if you enjoy white noise. I own a white noise machine to help me sleep and focus when I study, and these settings are excellent substitutes.

Filter replacement : I ran my units for 10 months on setting two before I had to replace the filter. The Alen corp told me that I would have to replace the filter every 4 months, but have found that to be false in my case. I found this to be a huge plus.

How effective is each setting:

The lowest setting isn't very effective if your room is polluted heavily, but is fine if your room has been purified and you want to keep it that way. Personally, I'd keep it on the 2nd lowest setting.

The second lowest setting is best for keeping the air purified, but lousy for cleaning the room when the allergies are really bad. For a light allergy day this is a fine setting, but for pollen season it won't cut it.

The third setting is all you need for a room 200 sqft or less during the worst days of pollen season. It'll clean the room in a snap and your allergies will vanish. After about 30 minutes on this setting I can feel my nasal passages clear up and my breathing becoming much more relaxed.

The 4th setting is the only setting capable of cleaning a room as large as the maximum sqft listed by Alen. I wouldn't recommend this unit for a room beyond 500 sqft when you are in the thick of pollen season. It really works best in smaller rooms, and I have found that the effect is drastically reduced when I move it into a larger room.