Best book ever written in mainframes... Comprises of all the topics and extremely well written. Alexis leon has been my favourite author from college days.. I have read this and always refer back to it whenever i require. Nice Q/A at the end.. Adds value to the book... :)

IBM Mainframe handbook contains one chapter on each topic like ISPF, JCL, REXX, CICS, COBOL, VSAM etc . But nothing is covered in detail, no practical examples. Mainframe professional should not refer this book. Its good only for answering questions during job interviews.
I would suggest books like JCL Primer, Practical MVS examples or any Murach's book.

This is a good book for the starters, hence if experienced professionals are looking into this for quick reference, I would rather advice them to go for the Black Book, rather than this one.

As for the freshers in this technology, I would suggest them to refer this one before shifting to Black Book