I have been using the chrome browser for a while but did not have a chromebook. I have found WiFi coverage to be spotty. In fact, it is even spotty just moving around my office! (Rather like cell phone coverage 15-20 years ago.)
I now have an Acer C7 chromebook and am able to write and run programs offline using Chrome Prolog, Python Shell , and Sole 64 BASIC. When online I can use things like codepad.
Chrome OS certainly does boot up fast.