FD has some issues, like the fact that they never listen to requests to add airports, etc.
Their map is the best feature, and they focus heavily on the airplane type. Good that they use the ICAO codes for aircraft rather than IATA.
Too bad that I have to fill in the airport in case they don't have it "in stock" though. That means the airport statistics are inaccurate rather than incomplete.
A new similar website (for me) is JetItUp. It has more airports, which I really appreciate (in fact, haven't found one they don't have!), but fewer/less-specific aircraft types. Also the map... I don't like it as much, but it's more correct for me given the extra info. They don't have full statistics on plane types, which is a big minus...