I just used Channels in a personal project and it's great! My requirements were mostly basic and I haven't put it into production yet, but everything has gone smoothly so far.
I made something like a cross between a chat room and reddit. There are any number of possible rooms (like subreddits), with new top level posts popping up in real time, and when you click on a post, it expands and the replies become visible as a comment chain. It's not done yet though. For a while now I've been trying to do as much as I can on a single project for one week, and then start another. I definitely plan to come back to this one when I can.
This week I'm using Channels again too. I'm making a head-to-head Minesweeper web app where you can challenge and compete against other players. After finding an opponent, essentially you'll see your own board and your opponent's board side by side, and each players' progress is broadcast in real time via Channels to one another.
