Got my Chromecast today (minus the Netflix offer, AFAICT)..
Had to enable UPnP on my router (something a novice would probably cringe at).
Couldn't get my Moto Razr MAXX to reliably see the device throughout the setup, and had to continue the setup on my Tablet ISamsung Galaxy Tab 2).
That's 2 strikes against the Chromecast right off the bat.. A "noob" who maybe on has a tablet or phone that is "incompatible" with the Chromecast would probably return the device at this point.
Once everything was up and running, things were a little jittery on the video side, but I have a feeling the Chromecast was doing some background tasks at first. After about 1 minute on Youtube streaming, everything settled down, and Youtube, Google Music and Movie, and Netflix testing went well.
I am going to test the casting from a Chrome tab and report back.
Yeah, I got some Rokus.