It depends on what you mean. Rails is the fastest mechanism for developing interactive web applications. It does have two distinct disadvantages though. It requires you to learn the Ruby language, which is a bit less well-structured than (say) C++. It also tends to make applications look a bit "samey".
The future for Ruby on Rails developer is extremely bright.
Yes, mostly because the software industry trend right now and in the
future is to use scaffolding tools like rails to build applications,
both web and otherwise. One wouldn't want to pigeon hole themselves,
however, into being proficient in only one type of scaffold or