i have a pair of clipless pedals from look on my road bike, and i really like the efficiency they provide.

the drawbacks - i still cannot easily clip into the second pedal. it always seems to be upside down. while this is fine when you're starting flat or downhill, and have room to get clipped in, it's a bit scary when you're trying to cross a road and your foot slips as you try to clip into the second pedal. also, walking on cleats is just not fun.

i haven't tried clipless pedals designed for mountain bikes that allow you to clip in on either side, and have the smaller cleats, but i'd like to.