Chromebooks are still growing. A built in SSH client can be access via CTRL+ALT+T and I've made use of this numerous times already.
Any review of the OS isn't necessarily fair even though it's available now because it's constantly changing. You will be able to review the same product a year later and have a completely different view since the apps available along with the updates to the OS will change dramatically.
Good point about the Os update cycle. Chrome has been getting updates rapidly and each update brings new features. I don't expect Google to launch Chrome OS and coast; they seem to believe big that a lot is riding on this system. That should prove to be good for those who buy in.
That becomes one of its strongest points the constantly updating OS and making it easier for everyone as everyone will be on the same OS update and all applications and etc will be updated at the exact same time as well.