Okay, I'm pretty impressed with the Chromecast...
Recently, I helped a friend hook up a new Chromecast to their HDTV. They didn't have an Apple TV or Roku (though they did have a clunky old school Google TV). I have to say, I was pretty impressed with it!
Yes, yes, the ugly power cable sticking out the side of the device leaves a bit to be desired, but for $35, it's cheap and pretty easy to setup. Nearly every app we tried had proper Chromecast support and it was easy to display content on the screen in the living room. And it seems like more and more services are getting updated to support it.
I think this is a great device for someone who might not already have an Apple TV or Roku. There's some things that might be a hindrance (e.g., no universal remote support), but controlling the device via a smartphone or tablet is pretty nice. I suppose that's the main caveat with this -- unless you're comfortable taking content from your phone and basically beaming it to your television, you probably don't need this.
See previously: Frank's interesting discussion about why one would purchase a Chromecast (see here: www.engadget.com/discuss/sell-me-on-why-the-chrome...)