I've got this one (
http://sanyo.com/xacti/english/products/vpc_wh1/index.html), kinda the newer fancier version of the one you are looking at - Here's what I've found with it.
- No custom white balance, so the underwater videos are a little blue, depending on your lighting
- For indoor videos, you need great lighting... doesn't take good video in low light
- You loose HD quality when using zoom, as long as you don't use zoom, your images are pretty good quality.
- The HD is probably upscaled, it doesn't seem like "perfect" HD. It is a shame that it only goes up to 720P.
- Videos in natural light are great, and it is really easy to use, anyone can figure it out. It handles abuse quite well.
- And of course, it does go underwater! It is really nice that it uses SD cards, since they are cheap and very easy to come by.