Rails is fine but didn't age well, specially the lack of strong functional programming support. Other nag is that it's hard to not do things the rails way - this monoculture reinforces the appearance that is fine because people looking to do something different just don't use rails. And when you "scale" rails is not really rails that scales as much as it is the architecture - it could be applied to other frameworks. Still if you are familiar you can write stuff really quickly.