Full Disclosure: I have not used AX. I have been thinking about starting a program and have been researching AX for about 3 months. I have limited my research to sites and articles not affiliated with AX. My 4 star rating is based on what I've learned. I can't give it 5 stars without actually trying it.
By all accounts, it's a positive experience; but if you read the review above, you already know that. I'm interested in the negatives.
The most prominent complaint I've encountered is the program's lack of leg work. The program's defining mantra of building lean athletic muscles seems to stop at the waste. There are leg based exercises, but they seem to based on dumbbell work and lunges. The takeaway is that if you're looking for huge leg gains, AX may not be your program. You should also note, if your looking to build huge muscles, AX isn't your program. The point of AX is to improve athletic performance, not to make you a professional body builder (If I could have typed that in bolder letters, I would have).
The are other sporadic complaints, but most seem to be superficial and/or petty: videos are too long or he talks too much or I don't like his voice. Others where things like "It didn't work for me," which could mean anything from the user didn't stick to it and wrote a bad review because he/she regrets having spent the money to the fact that not all programs work for every one. But, but who knows.
One attractive aspect Of the program, and one of the main reasons, initially, I was drawn to it, is the under $67 price tag since most programs run $150 or more.
All in all, I think any program is only as good as the effort you put into it.