This is being written on a Chrome Cr-48 Notebook. Yes, I was lucky enough to be chosen to pilot test this notebook and operating system, and I've been using it as my full-time computer since a few days before Christmas. :)
Let me first say that Google is not trying to compete with tablets or smartphones with this device, nor is it really in competition with other netbooks or notebooks. The Chrome Cr-48 is a different way of computing, not necessarily better or worse than other ways, just different. As a long-time tech geek, this is something I am still getting adjusted towards.
In many ways, it is a more secure way of computing than what we're all used to, since none of your data exists on the device itself because you can't store anything on this notebook. And as long as you are signed out of your google account, your data in the cloud is secure if you should happen to lose this notebook or have it stolen. There's also no antivirus or any other application that you have to keep updated, the Cr-48 updates itself in the background.
This is more than Chrome the browser as the notebook, though. I would bet that most people don't know (and most reviews I've read don't mention) that you can jailbreak this notebook (legally) and boot up Ubuntu on it. And if you're a software developer, there is a Developer Mode on the Cr-48 for you. So, yes, you can do programming on this little notebook, or you can build applications (not just browser extensions) for the Chrome Web Store. I'm not a programmer, so I haven't entered Developer Mode or booted into Ubuntu, but so far, I've been able to use this notebook to do pretty much everything I was doing on my Windows desktop with the exception of iTunes (but Pandora works fine).
I've even managed to crash the Cr-48, but I think that was a fault in Adobe Flash, which I understand Adobe is still working on. To recover, I simply rebooted the notebook and everything was back to normal.
I even use the Tweetdeck Chrome application for Twitter (found in the Chrome Web Store), although I do prefer the desktop application which has more options. Still, it works. I've watched full-length movies on YouTube and Hulu with no buffering problems. Facebook and Twitter, and all of Google's applications work just as they did on my Windows desktop.
So far, I'm pretty satisfied with both Chrome OS and the CR-48 Notebook.