When you by a fighting game guide typically what you get for your money is frame data, combos, general strategy, and pictures, not to mention convenience.
Frame data: I find this useful in guides because they provide a clear and easy way to read frames w/ no computers or spreadsheets. I like how guides lay the spreadsheets out for you. Seems easier for my mind to digest. However once a game is updated they can potentially become useless.
Combos: Most guides have good starter combos for learning characters. Once you learn a character though you will be ready for better combos from the net or of your own creation. The SFxT guide has good combos but many improved ones can be found by now.
Strategy: This is where guides differ some have great in-depth strategy like the Umvc3 guide (best guide ever) or more of a general overview. I guess some don’t have any or bad strategy too but i don’t own one of those. As far as the SFxT guide goes the strategies are good but don’t expect the game to be laid out in front of you. Remember these mechanics are fairly new.
Pictures: Guides have many pictures and can help link the frames for moves as well as their range. The SFxT guide has pictures for every move as well as pictures demonstrating more advanced techniques so you can follow along. The guide also includes bonus art if that is your thing.
Convenience: When you buy a guide your generally buying convenience. In this day and age the internet has all of the answers However there is a lot of internet to go through sometime just for an easy answer. I always find a fighting game guide good whenever something randomly pops in my head and I think “How or will that work?”. Then I can easily just look and compare some data and voila!
Opinion: Personally I like guides mainly because if I have a question or need specific info I don’t need to search and compare. All the info you need is all in one convenient spot. I do find all the strategy information worth something even if I already came to the same conclusions as the authors. Pictures helps me recognize moves in conjunction with frames. Combos are good but will be basic in the long run, helps me learn to fight early and I can always build on them. Frame data is great even if it will be outdated eventually.
The SFxT guide is about $13. Not a bad price for the info in my opinion.