So people, I've been playing Alleg for the last week, and I really like it.
The hotkeys are different, so FS players may get lost, and the flight physics is different. The game uses directional thrusters a lot more than FS (which only really uses it in Mods), so instead of turning only by turning the joystick, you might have to use upward, downward, left or right thrusters, which adds a lot of tactics. The learning curve is steep, and I'm still slowly climbing it. The game requires a lot of teamwork, and that's great. You must have a lot of situational awareness, and tactical thinking. It has a mode that is somewhat like an RTS, which is when you use the command view, to give orders to the other players, or to the AI Units (constructors, miners, etc.)
The game flows greatly, and has many factions that have varied ways of playing.
Graphically, it's not as great as FS2 (with MediaVPs), but has some graphical upgrades too. (Mainly to textures and backgrounds.)
By the way, the in-game training isn't really good, IMO.