I own a Suzuki GS450TXZ, and bought this manual as a supplement to the Clymer manual I've had for years. The first thing I noticed was that the photography and diagrams were excellent. Very close, clear and detailed pictures of the parts being worked on. I also found the text to be consise and straightforward.
If there is anything lacking in the book, it was that the bulk of it only refers to the 250 and 400 models. All information about the 450 was put into the last couple of chapters. One was expected to flip between the instructions for disassembly in the front of the book, then flip back to find the proper calibration numbers in the back.
In the end, though, I find the book worth having.