Vineet,

ROR makes a certain class of application very easy. Others not so much. If you are building an application with a limited number of data models where having 'user' vs 'admin' distinctions isn't very important, then you can get up and running with ROR very quickly. If you are building a more traditional application where there is a distinction between end users who consume and administrators who create, then Djanjo would probably be a better fit.

For the types of applications that I create for my job, neither is very good as the number of data models, large amount of business rules etc are beyond what most frameworks are designed to make easy.