I'm a bit tired of these sinatra like web frameworks these days. Repetitive url patterns are not that elegant. Why not simply building the API around the fundamental REST concept, the resource? And what about proper content negotiation? JAX-RS has a nice API without much boilerplate and it is more powerful than most "micro web frameworks".
I think REST is like the 3rd normal form of databases. In theory it's great, but in practice people only try to get close enough to the abstraction.