Upon some cursory googling I found that it's an almost direct copy of old versions of FlightGear, which is a free and open source (not to mention up to date) version of the same thing.
I saw it being peddled on a bf3 flight tutorial on youtube, just thought you guys might want to know.
Although technically legal, I find their business practises rather unethical. I find it dodgy that they've bought up or created tonnes of pages giving it unanimously good reviews.
http://www.youtube.com/watch?v=luS06fresHs where I found out about it
FlightGear's http://www.flightgear.org/flightprosim.html
http://en.wikipedia.org/wiki/FlightGear#Commercial_redistribution