Hi Sourabh,
Thanks for the compliments!
The Spring Security ACL subsystem is certainly intended to be extended (in the truest OO sense) to develop whatever functionality your business
unit might need. It comes out of the box with a very flexible system of inheritance and user/group/data relationship modeling that is likely to satify many common scenarios.
That said, it's very complex code which is written in a different style than most of the rest of Spring Security, and many new developers have a hard time getting their heads around it, so please do keep in mind the learning curve when rolling this out, especially to more junior developers.
The difficulty of understanding this part of the framework is one of the reasons I felt strongly about dedicating a whole chapter to ACLs in the book - this wasn't originally what I planned, but after reviewing the complexity of the code, I felt that I couldn't do justice to explaining it without having (checking my notes) about 35 pages of material on it
Hope that answers your question!
Best,
Peter
Author, Spring Security 3 (the Book), Packt Publishing, 2010
SCJP, OCP