A few years ago when I downloaded Aerofly FS 2, it looked pretty complete to me. And it got even better along the way: To my suprise features were added (like new planes and helicopters) without me having to pay anything for it.
If you are looking at other flight sims you might miss a lot of features. But I for one would not call a Cessna 172 incomplete because it is missing fly-by-wire, an HUD or a jet engine - Cessna never advertised the 172 to be a combat jet plane.
And regarding the usual sentence "this game is dead because I do not see any new development for some time", you might consider chess a very dead game by now, because it has not changed for some decades.