Micro-frameworks are a great way to get into web development if Rails is too intimidating. I cut my teeth on Sinatra. As I got more comfortable I started using Rails.
I now use Sinatra only if I'm absolutely sure that the project is not going to need anything more than a single page of code. I've re-implemented Rails functionality, poorly, way too many times.
Cuba looks much leaner and meaner than even Sinatra. Can't see many use cases for it, maybe if I were implementing a non-standard API for, say, a game engine. But who wants to use Ruby for a game? Pure HTTP applications, I can definitely see the appeal. But the second you need to serve HTML, you're gonna want Rails.
I now use Sinatra only if I'm absolutely sure that the project is not going to need anything more than a single page of code. I've re-implemented Rails functionality, poorly, way too many times.
Cuba looks much leaner and meaner than even Sinatra. Can't see many use cases for it, maybe if I were implementing a non-standard API for, say, a game engine. But who wants to use Ruby for a game? Pure HTTP applications, I can definitely see the appeal. But the second you need to serve HTML, you're gonna want Rails.