IMO, better than a book, start here
http://www.largeformatphotography.info/ If you do a search on the forums there, you will find plenty of discussion on which are the best books to buy. The topic seems to come up on a regular baiss every month or two.
Also, I find you cannot lump MF and LF together. This is from direct, personal experience. They are very different animals. I still own and use my Mamiya, and I have 4, 4x5 cameras, in addition to my 35mm and my digital SLR.
In medium format, you are still shooting with a roll or film or a digital back. In large format, you are shooting one sheet at a time. You are also playing with movements, and that's a whole new kettle of fish. Not hard to learn, or at least not as hard as some may make it out to be, but it does require a different mindset.