I think it's a pretty fair price. The PDF costs less than a single 1/300th plane, and about the same as several 1/600 planes.
A typical Pacific battle, with Zeroes, Vals, Bettys, Wildcats, US dive bombers (can't remember the name), and targets (naval ships) costs about $10 USD using this system, plus the price of printing and the time of cutting and gluing. I think that compares favorably to doing it with miniatures.
I suppose it would get cumbersome if you want to field every variant, but for a quick-play game intended for easy set up and 20-30 minute game play, I don't think that's as big a consideration.
As for info about the system, the preview file gives a fair amount of info---movement (I think at least) is the most important part of an air combat game and you get a good briefing of that.
The art quality on the counters is better than "very plain" in my opinion and has better resolution than you see in the preview (typical for PDF downloads, I think).