Hello Anujit,
most developers find the introduction linked here very useful:
http://scn.sap.com/docs/DOC-45425
If you have a question, please feel free to ask.
Inside SAP a lot of colleagues know about BOPF, as many SAP application are built on BOPF (e.g. Transportation Management, EHSM, most parts of Business ByDesign)
Outside SAP there is also a growing user group. The reason for this is that if you have to built a business application on ABAP, using BOPF will increase the success of your project. The architecture is proven and you can benefit from reusing must of the core infrastructure. The saved development time you can invest in the functionality that really makes your application unique.
So if you are thinking of developing a business application with ABAP, you should definitely have a closer look on BOPF.
Best regards
Tilmann