I used the Chromebook (Samsung 5 Series 550 3G laptop) for about eight months. What is my verdict? Should one buy a Chromebook? While it is amazingly efficient to use if one primarily uses the browser for everything including watching videos, it is not for those who must compile on their own computer, must use desktop applications, or care about high frame rates in games.
ChromeOS usage, on a daily basis over the last eight months, reminds me how much time one wastes to update on most operating systems and applications. I can safely say that I've wasted no more than a minute due to updating the Chromebook since May 2012. Reboot, when necessary to run the latest version, is within seconds. I cannot say the same for anything else including phones or tablets. The sole exception is perhaps an Android device with the enabled option to auto-update applications without user input.
If you use a browser most of the time and don't need to use desktop applications, one could be happy using Chromebook especially when already using Google's services. There is a curve ball though. Wireless printing is not easy if you don't have one of the Google Cloud Print enabled printers. Without one, one would have to use Windows or Mac with the Google Cloud Print option enabled in Google Chrome in order to wirelessly print from the Chromebook.
Pros:
Price ($200 to $500)
3G
Minimal downtime (seconds)
Relatively secure
Cons:
No Skype (could use Skype chat on imo.im though UPDATE 3/2014: imo.im no longer provides that feature)
No high pixels per inch resolution options such as currently seen on large iPads or Nexus 10. *UPDATE: Google released Chromebook Pixel with a high resolution screen.