I have a few thoughts to share about them as I checked them out abit while shoppping for my Kayak.
I like the pedal power as a way to keep your hands free to cast while still being able to paddle forward. Not sure if they work in reverse which could have it's uses.
The flippers or paddles under the yak can be limiting for the very shallow water use. Also if you drop your paddle and don't have it leashed and it sinks, your not stuck without propulsion.
I believe they can be outfitted with a sail, which can be desirable on windy days or long trips. Pretty versatile Kayak in all.