There are 2 main problems with this game.
1. I suck at it and do not have much fun as a result. Now, you may laugh, but I don't think it is all my fault, or more importantly, that the lack of fun I have as a result of my suckage is my responsibility. The main role in the game is that of the fighter pilot and there are a number of players who top the leaderboards and kill everything in sight. For a normal person however, it's a matter of struggling with the mouse aim controls until you are inevitably shot down. And yes, there are youtube videos to improve your strategy but they did not help me much (especially due to reason No. 2 below). Besides the main role, this game does not really have a supportive role. Well, the bombers are sort of a supportive role. At one point they mattered, but at the moment, after a number of gameplay tweaks by the developer, being a bomber pilot now means seeing how much time you will waste trying to gain as much altitude as possible before you are inevitably shot down anyway. Other roles, like fighter-bomber, don't seem to matter at all in the arcade mode (which is what everybody plays). In the end, the game features can be defended, but if I (the consumer) cannot find a way to have fun, it is your fault as developer. This game really needs a co-op mode, which I have not seen yet.
2. The gameplay balance has been changed a number of times. This alienates a number of players each time. There was a particularly large change in one of the patches that lost a huge player base. Essentially, just because you developed a successful strategy in a specific plane that you like, does not mean that your strategy will remain successful after the next patch. Just because you like this game now, and you invest a lot of real money into it, there is no guarantee you will like it after the next patch. This is unfortunately a problem with a number of other free-to-play games as well.
On the bright side, there are different game modes and simulation levels, depending on how much simulation you like. There is a single player component (thought using it is a bit confusing), which can be fun as you engage in large battles or specific complicated missions, though some of these missions are strangely impossible, while others are relatively easy. The graphics are quite good and colorful. There is modding support for airplane skins. The main problem is definitely the balancing act and the developers can't get it quite right.