1> What is a best Feature in Spring 3 that makes it a class apart from the rest of the frameworks..?
Being a light weight framework that supports a full enterprise stack with dependency injection, aspect oriented programming and integration with a lot of other technologies while simplifying them
2> Differences Between Spring 3 and previous versions ?
take a look at
this
3> Please suggest a Worth Buying book /Downloadable e-book which has got more of practical in-depth with theoratical exposure as well.?
I've always been a big fan of spring in action. Latest version is on spring 2.0, but third edition is currently in MEAP. Don't know if there are any books currently available for spring 3. Finally, the second best book IMHO, is the spring reference itself. You can download it from spring's website