I had a chromebook for a while, it was a reasonable little thing. I still have it actually, but never use it anymore now that I have a MBP. The processor was a bit underpowered for my taste, I would have traded an hour of battery life for zippier compile times but it's not really what the thing's designed for so I can't really complain. If I couldn't afford my current computer I'd probably use a chromebook again.
ChromeOS is kinda dumb though, I installed crouton after like a week. I think the market of people who would be happy with it is pretty small, but IDK, google certainly has done more market research than me. I mean it was well designed in and of itself, Chromium is a very nice piece of software. But if NaCl is all you have for native execution, and even that's sandboxed to the point you're still limited by the chrome APIs, then I just it just doesn't make sense as a platform for most developers who aren't already doing webapps (which means no exclusivity, which means a much harder battle for adoption).