I put one of these on last year. http://www.amerimerc.com/pool_supply...ety_covers.asp

I installed it myself and drilled the anchors with a hammer drill I rented for a day.

Looks great and seems to be a quality product. I've only had it for one season but I'm happy so far.

It does let a lot of fine particles through and algae will grow under it because enough sunlight gets through.
If you have a freezing climate the snow and ice will pull the material into the pool no matter how tight you make it. Generally this isnt a problem and it pulls back into its drum-like position after it melts.

I'm going to get a "black-out" blanket for underneath that is supposed to keep the pool cleaner over the winter and block all sunlight.

Overall I'm happy with my decision and prefer it over a solid cover. It is easy to put on and off (30 minutes) but I wouldnt want to do it very often or by myself.