Two weeks or so ago I had the chance to paddle Yoav's W Boat. Here are my impressions:
1) It is MUCH narrower in person than it looks in the images (this is a good thing)
2) It is VERY stable
3) It is as easy to paddle standing as sitting, and is very stable fore and aft as well.
4) You CAN paddle it with a single blade, but I admittedly found it a bit easier with a double-blade (I probably needed a longer paddle, though...I had one of my C1 sticks).
I'd take the W Boat in up to class II (mild class II) water (Ok, I'd personally take it into mild class III water (this boat could be fun on the Sac
), but I wouldn't recommend it in general. The boat is VERY stable, you can bounce up and down in it (it's quite fun, actually), and the plastic is good stuff (hard enough not to get scratched too badly be dragging it over the ground or "penguin leaps", but suprisingly light for it's size). For a rec. boat it would be great (e.g. instead of an Old Town Loon or something like it), or any type of boating where you want a durable, stable platform.
Yes, it's still quite fast (not sea-kayak fast, of course, but I'd guess faster than your average rec boat).
So, for a boat to kick around on the lake or slow-moving water (and for kids in these conditions) it's defintely worth checking out. I'm going to paddle it again when it warms up a bit around here to really have some fun with it