No it's a great tool for learning without going to the fully fledged laptop. She's able to work through codecademy training courses, tools like ShiftEdit and Cloud9 IDE are the next step. Tons of tools out there now for using a chrome book - maybe not for a power developer but for a beginner, particularly one who I don't want to trust with an expensive MacBook just yet, it's good enough to begin with.
I'd expect an actual "power developer" to be able to cope with any kind of environment! :-) A proper hacker should be able to make a Chromebook do virtually anything.
