They are difficult to clip-in - spring tension, and therefore knee breaking to get your foot out. The ones I had had no tension adjustment.
They get stuck upside down, making it tricky to get your foot in.
They had too much float for my liking (which wasn't adjustable).
They were heavy
Good bearings, and cleats last for ages
Yes, I'm not a big fan!
I like Look Keo at the moment but the bearings don't seem to be that great and the cleats wear quickly.