I'm playing the alpha right now, and it's awesome. I want to post some screens so badly but I can't.
Gameplay is awesome, if you love planes you are in for a treat. The visuals are gorgeous (the trailers didn't lies) and you can click everywhere IN THE WORLD and spawn with your plane to fly for a trip.
I flew over my house (in a little town of 5 000 inhabitants) and it was awesome. I visited Tokyo, Paris, NY, Washington, Dubai, The pyramids of Gizeh and many other locations and the render is just WOW.
Everything in the cockpit is clickable (and work as intended) The live traffic is working really well (for planes AND boats), the sound is also playing a great part of the immersion.
This game is gonna be a revolution, I believe it.