I like to take my kayak on the lake near my house and fish in the summer.  Very relaxing and fun.
I've never done either, but it seems fun.
Its different than a canoe by the the sitting position of the paddler and also the number of blade s on the paddle.
I find that canoeing on the open lake waters are one of the most serene experiences that one could have.
I love water and a Kayak is so low to the water and using the double bladed paddle to pull on one side then the other, is very good exercise too
That seems like it'd be a lot more efficient than using a single oar.
Yeah, most are closed deck, but there are sit on top and inflatable kayaks that are new and getting popular also.
I would be nervous to not sit inside my vessel. I would think that they'd be more top-heavy and be easier to tip.