The flipper is great if you replace the blades every now and then. I've been using mine for probably a year and a half now, with great success. My problem is I have too much crap growing around the tank now, so it's getting harder and harder to clean without scraping corals on the inside (even with the super-thin flipper).
Highly recommended though. Not the most powerful magnet, but for its size it's very good. I'd like to try the Tunze nano scraper at some point too, but haven't felt the need.