Absolutely love them, have them on every bike I own and have owned in the past 15 years (albeit the early ones where Magnum pedals not frogs).
I got run over by a bus many years ago and snapped my knee a touch, no matter what pedal I used I had huge pain so I kept on coming back to these as I never even had a twinge with these. They are firm and secure but offer a large degree of float (very controlled float with the frogs, not so controlled with the Magnums - your foot would merrily wing with those..)
Great for mud as there is no mechanism to get clogged, only downside i can think of is that they can be a bit hard to tell when you're clipped in sometimes (especially when its muddy), but 99% of the time you are a just don't know it!)