Hard to say from the MSDS, but it's likely an organic acid salt. While they say it's "acid free" in the traditional sense, ie, they are not adding a mineral acid like HCl to the formulation, it's still an acidic chemical as evidenced by the pH of the solution being < 1. It gives off carbon dioxide and monoxide as combustion products as well as nitrogen oxides so it likely contains an amine group. It may not change the pH of water all that much but it could increase your chlorine demand depending on how easily chlorine oxidizes it.
It's probably fine to use, but I'd keep an eye on your FC. There are few sparing reviews of this stuff online and they all seem to indicate that it requires just as much "elbow grease" to use this stuff as it does to use muriatic acid. So since it's not a huge time saver, it may not be worth the extra cost.
