To be honest, I'm still not sold on Vessel's business model, which posts original web video content a few days early to paying subscribers before it goes out to more general portals (usually YouTube). But the Android app seems more than serviceable even in its beta form, and the developers are adding features quickly. Case in point: the latest update adds Chromecast compatibility, which no video app should be without.
The feature works exactly as you'd expect it to: start a video and look for the Chromecast icon, then connect to a local Chromecast or Android TV device. You can connect on the main viewer screen as well, if you don't want to scramble to send your video as soon as it starts. Performance is fine, and the early participants in Vessel seem very committed to delivering high-quality video (in a technical sense) to the service.
I could go on about why Vessel probably won't make sense for any but the most dedicated of fans, and even then, only those who are dedicated to a relatively limited field of Vessel content providers. Oh, look, now I have. Vessel is a free download for Android 4.1 or later, and requires a $3 monthly subscription after the trial period. There aren't any other major additions in the changelog.