First thing every JAVA book praises is it's cross-platform compatibility. True JAVA code can be developed & build and run in any platform JVM supports. The only problem is the user experience of JAVA application varies in Windows to Unix.(excluding web apps) Applications looks & works different in Windows but looks awkward in Linux. The real use of JAVA portability is to develop in windows and deploy on Unix server. There were few JAVA desktop application but performed badly and never drew user attention.
Now to Google, they choose HTML for cross-platform cross-browser applications. Will they succeed or they'll follow the way as JAVA? Google talk plugin doesn't work on all platform, definitely not on Linux yet. So, what's the real purpose of Chrome OS which is based on browser - HTML & JS? An device to access Google services and as an browser? If that's the case why would people buy Chrome net-books instead of iPad?
Chrome browser is definitely better than Firefox or IE but can it do things more than an what an normal browser does? Chrome OS & net-books can be of much useful to non-IT businesses but for the masses it can't be sufficient like iPad.
OS we know hasn't evolved much other than look & feel. We may have to wait to see how OS gets transformed and how we prefer to use. Will we ever accept give full control of our data and what application we use to Google or Apple or MS?
Advantage of Chrome is it's browser & security. Dis-advantage of Chrome OS is also it's browser. I could buy Apple or Ubuntu laptop and can still enjoy the benefits of Chrome.