I think it's the best equivalent to an Apple TV in the Android ecosystem. Great performance and 4k, but way less apps (notably no Amazon Prime TV app).

If you're into cord cutting they do have an app for Sling streaming cable service.

Chromecasting to it is straightforward, and on par with Airplay. That was the one thing holding me to iOS for a long time.

Depends on what do you mean by that. nVidia ShieldTV is currently probably the best STB on the marked, it can hardware decode anything you throw at it (including VP9 and 10-bit H265), is less buggy than the reference Nexus Player and has access to most big network apps.

Large exception is Amazon's stuff, because Amazon deliberately refuses to support Android TV because they're pushing their own crap.