I'll give my input since I've used their package before (and no, I'm in no way affiliated with them). You may have noticed that they're currently having a sale where for 99$ you get access to most of their content across a lot of different topics. For instance:
- C++ Programming for Game Developers - Module I and II
- Graphics Programming with DirectX 9 - Module I and II
- Game Mathematics and Math Primer
- Artificial Intelligence for Game Developers
- Introduction to Robotics
- Video Game Console Design
I honestly believe that for that price, that's one of the best deals of this kind I've ever come across.
I haven't completed all of the courses yet, but from what I've seen so far, the amount of content and detail packed into each of them is at least as high as most books you could buy for each individual topic. For instance, just the textbook/workbook for the first DX9 Module is over 1000 pages long, and that's not including the actual presentations which also have a full voice recording.
To put it shortly, I believe that the value in this case (for the 99$ deal) is ridiculously high for the amount of content you'll get. I've built up quite a large library of game developments books over the course of the past few years, and this package still ranks up there on the list as one of the best investments I've made.
The only drawback I see is that the courses (at least the ones I have) are mostly aimed at beginners, and are a bit outdated in terms of dealing with some more recent techniques. But that's usually the sort of thing you will only learn after reaching a more advanced level anyway, so the courses serve as an excellent starting point from beginner to intermediate level. Although more recent techniques are being researched every day, the basics still apply so in my opinion all of these courses are still very relevant.
I just noticed the following disclaimer on the site:
Advanced Graphics Programming with DirectX course content (coming 2012)
So I think that will probably address the concerns on my last paragraph.