Well, Rails was talked about plenty back in the day (with its fair share of expletives), and it's proved to be anything but a children's toy. Regarding Closure

Well, Rails was talked about plenty back in the day (with its fair share of expletives), and it's proved to be anything but a children's toy. Regarding Closure and its libraries, my impressions are that it gives tremendous maintainability and structure when you have a large team and a long-term project, but there's still a lot of boilerplate when you need things like a simple data binding. Having searched around, I've found that Angular (1.2) provides a good balance between structured, easy-to-find-things code, and fewer keystrokes to iterate fast on features. I wish React were like that, but the lack of best practices in the Flux architecture makes it hard to know where to put things - I found I was constantly worrying about shooting myself in the foot when I made architectural decisions in React. I do think that Angular's going to get a Python-like version split, and it's refreshing that plenty of people are still writing Python 2 libraries... because I'm not leaving Angular 1.2 any time soon!