I think it depends on what you want to do. If you want to learn to speak Cantonese these books are fantastic, as is the English-Cantonese Dictionary (Cantonese in Yale Romanization) by The Chinese University Press (ISBN  962-201-970-6). If you want to learn how to read and write Chinese then these books will not be of much help to you.

Thanks for the suggestions.

Well I do want to learn cantonese. Though learning to speak it sounds limited compared to reading and speaking.

Dont scare by the name of books. They start from very simple dialogues in each unit like any other books for beginners.(*^__^*)

That's a issue. Sounds like it makes learning cantonese harder.