I'm not quite sure how to handle this one because it's basically an animated version of a part of the FF7 story. So if you haven't played the game then you won't know what is going on at all. And if you have played the game then you already know what is going to happen. But all that aside, there's just something fun about watching the FF7 characters in anime form.
This one-episode story mainly revolves around Zack and how he and Cloud are on the run from Shinra. It does a good job of clarifying some elements that didn't play out as well in the game -- like Cloud and Zack's ride in the truck, and how exactly Zack died. The animatoin is great, and the music is good, though nothing about the later really sticks out in my mind at the moment. So if you're a fan and get a chance, then check it out.
It was originally released in Japan as an extra on the FF: Advent Children DVD, but for some reason it wasn't on the US version for some reason. So sad.
And that's pretty much all I have to say about that. :D