So, I spend the weekend with Chromecast, and came away impressed. As a Roku 3 owner, I wanted to see how Google's SDK implemented in apps/browser mirroring approach compared to the Roku's native apps approach.
Chromecast's app integration with YouTube, Play Movies and Netflix is simple and elegant, and preferable, in my opinion, to the Roku UI because it uses the native app interface instead of a device-specific one. Chrome browser mirroring isn't nearly as good a UX, but that's fine. It still gives you the ability to consume pretty much whatever web video (or audio) you want on your TV -- and it's not an end solution anyway, it's just a workaround to give people HBOGo, Showtime, Hulu, Amazon, et al. until those respective apps implement Google Cast.
The bottom line? At $35 Chromecast is a great value for money, and that value's only gonna get better as more apps jump on the Google cast bandwagon.
My full review can be read on +Engadget