I've been using the Cr-48. By not having Windows and a registry, the computer doesn't slow down over time. By not having applications checking for updates (Windows, Office, iTunes, etc.) the computer doesn't slow down. With no antivirus software, the computer is not bogged down while doing other things.
I've been dealing with this type of technology for more than 30 years and this is the best concept I've seen for the "typical" user. If you're accustomed to having multiple photoshop images open with 12 layers in each while playing a video, listening to iTunes and doing Microsoft Office updates...well this product might not be for you. However, if you can visualize an analog in the web app world for nearly everything you do, then you'll love the whole concept of cloud computing.
No more backups!