Chromebooks are one of the most secure devices you can give a non-technical end user, and at a price point few can argue with, but that security comes with a privacy trade off: you have to trust Google, which is part of the NSA's Prism programme, with your data in the cloud.
Even those who put their faith in the company's rusty "don’t be evil" mantra may find Chromebook functionality limiting—if you want more than Google services, Netflix, some other Web apps, and maybe the Android app store, then you're out of luck.
Geeky users willing to engage in some entry-level hackery, however, can install Linux on their Chromebook and unleash the Power of Torvalds™.