Absolute rubbish. If you follow the author's advice during the game you will easily get taken down. The guide does contain some back round info on the gangs and weapons and some nice screenshots, but as for helping with the game, it does not.
I was stuck at the part in the prison and I bought the guide to help me, I opened to that page and tried what the suggested with no joy, so I then just did the best I could and ended up completing the game without it. It is a waste unless you want it to complete the harder modes to get a higher star ranking, but otherwise it is best avoided and not a sound investment.
The author and publishers of this guide should take note of the official Silent Hill 2 strategy guide, as it's been well written with enthusiasm