This is the fan i've been looking at getting (along with the HS). I've read as many reviews as i can find on it, and here's my take so far..
Noise:
at full speed, its a bit noisy, but turn it down just a tad, and you get great cooling with minimal noise. All the reviewers said the noise is from the rushing air, not any high pitched fan whining or anything like that.
Cooling: All the reviews i've read put this right at the top of the heap, even with the SLK-900 + high CFM fan, despite the Aero 7's low CFM rating. They all say this is because of the much greater air pressure it produces over normal axial fans, and also because it eliminates/reduces the "deadzone" in the center that most axial fans have, which is generally the hottest area on the heatsink. You can also change the orientation of the fan on the heatsink to best fit your cooling setup.
Appearance: Its a pretty unique design, and IMO looks pretty sweet.
Cons: With the Aero 7 non Plus version, some cases/mobos had problems with the thumb clip used to attach the heatsink (instead of a screwdriver), it was too big and had to be bent. The aero 7+ supposedly fixed this problem. The front panel mount for the fan control doesn't fit very well (the PCI slot mount works fine).
Price: I've seen it around $30-$35 + shipping for the HS and fan, which is a pretty good price considering how well it seems to perform.
Of all the reviews I read, the tests were performed with the stock heatsink that comes with the aero 7+. So I don't know how'd it perform with a different heatsink. Remember, this is just my opinion based off what i've read.. i haven't actually had any experience with it yet, but it looks like the one i'm gonna get.