APM 2.X is about 10 years old but. Used this on a 450 Flamewheel Quadcopter. Used to be a good learning tool but is no longer supported by Arducopter. If you are looking for the latest, check out Betaflight F3 or other newer technologies. However, it was ideal for me to be able to upgrade to an affordable Quad FPV 450 build with all the bells and whistles for about half the price. Just be prepared to spend a lot of time researching and soldering in the Arducopter archives. Worth only my .02.