It seems we end almost every Chromebook review with the same disclaimer: They're not for everyone. And we stand by that: We cannot, in good faith, recommend a Chrome OS device to everyone. There will always be people who need to do more offline, and who need the flexibility to install whatever apps they want (Skype and iTunes come to mind).
But for folks who can get by doing everything in the browser -- and using Google services like Hangout -- Chromebooks are getting cheaper, more functional and more powerful. The refreshed C720 in particular is a bit snappier than older-gen Chromebooks, thanks to a Core i3 processor, and yet the battery life doesn't really take a hit on account of that heavier-duty CPU. And despite the improved processor, it's still reasonably priced, at $350. Good luck finding a Core i3 Windows machine at this price, especially one this portable.
Our main reservation in recommending this is that other PC makers are on the cusp of coming out with Core i3 Chromebooks, and in the meantime, Acer's is held back by a poor-quality display and cheap, netbook-like design. We're curious to see what other companies have to offer -- perhaps someone else will present us with something a little more well-rounded. Even then, the price would have to be fairly low -- the performance gains here aren't so huge that laptop makers can get away with price gouging. And as the price does get higher, you'll have to work harder to justify buying a Chrome OS device instead of a Windows machine. In any case, until those other models go on sale, the C720 remains a good value. And if its performance is any indication, we should have high hopes for everybody else, too.