just got mine today...and have to say, i'm a bit dissapointed. i bought this because of the rave reviews of it.
for those wondering about sound, its louder than a sonovabitch. and, possibly just mine, has a nasty little buzzing background noise. the plastic where the extension tube connects to the base and the fan was poorly cut and you damn well needed to pound the pieces together. but i will say it is very powerful, it really does move the air.
as for air circulation, well, i follwed the directions and what everyone says to do, and this thing is really just a powerful fan. On the high setting, you get a bit of a cool flow (a bit!) through the room, but the noise is almost unbearable. Its easily as loud as my air conditioner. Just a really loud, really short fan.
this would be perfect if it were just a bit taller and could actually be at my bed height.