I got one awhile ago. It is a great concept and a great price but needs way more support than it currently has. I'd love for Amazon Instant Video, Vudu, and MLB.tv to support it. I think this is Google's fault for how they are handling the non-beta SDK.
I also think lack of Miracast support is a lost opportunity. So many TVs (like all of mine) lack support for that technology but it seems like all newer Android devices are dropping MHL and HDMI in favor of Miracast. That sucks, because I used to use my Galaxy Nexus with a MHL adapter and Bluetooth keyboard as a sort of mobile computer in hotels. Now I have a Moto X and it only does Miracast. If the Chromecast supported Miracast, I could have used it. Its not like hotel TV's support it or will anytime soon.
It also only seems to support Dolby Digital Plus for multichannel audio, not that it matters for me because my TV only passes multichannel to my receiver if the source is the internal tuner.