no problems at all with the shop selling this item - it came quickly and was well packaged. I have a PS3 slim, and although this would probably be better on an original fat bottomed PS3 it still goes onto mine fine, it just has a bit of overhang - and don't we all!. It fits into the front usb ports for the controllers, and blows air from under the machine upwards. As far as I can see, most of the front of the my PS3 is sealed, only on one side are there any gaps that could have air pushed in by the fans, so only 2 of the 4 are actually doing anything - but that appears to be enough!
The only bad thing is its pretty noisey - so 4 instead of 5 stars - but you honestly don't even hear that after a while.