I'm impressed by CCP Games and the Frostbite team using this because I think they are both awesome (except wen it's ME: Andromeda) Being FOSS is another great thing and he features are pretty impressive. It's mobile friendly. I'm not a developer. So I can't say much about APIs although the promises look great. I also love Anonymous posting and polls (I'm a big fan of dpoll).

As for cons, it's not using https. This could be a temporary thing. But it's not really nice to greeted with a warning about the website not being secure.