Phoenix sits somewhere in b/w Sinatra and Rails custom/simplicity wise, while offering features that neither address, i.e. (realtime communication with browsers

Phoenix sits somewhere in b/w Sinatra and Rails custom/simplicity wise, while offering features that neither address, i.e. (realtime communication with browsers, native iOS, & soon android clients). "Qualitatively better" is a loaded question, but by virtue of Erlang VM, Phoenix apps can be distributed across a cluster without extra fanfare. You could run 20 Phoenix routers, load-balanced on a cluster, and everything like Webscokets/pubsub would "just work". i.e., no extra layer in b/w like redis or rabbit, no code changes, and no issues with things like sticky sessions.