I played the alpha and both betas, then picked the game up on release. I love it!
The open mountain world looks stunning, and i find the gameplay is very satisfying; you can get that really rewarding "yeah I just nailed that feeling". The way you can just teleport around the whole map with zero load times is ace and what games should strive for.
I mainly ski with a bit of wing suiting, and occasionally paragliding to reach new drop zones (spawn points), though often I just heli into new drop zones as tickets are super cheap (and free later on).
Not really tried much multiplayer yet but I believe that should only make it better and I'm hearing great things from those who have played lots of multiplayer.
It can definitely be improved and can frustrate now and then. But for the first in the series I think it's great and shows lots of promise. I can imagine it's not a game for everyone though. I really enjoyed SSX games, Amped series, Skate 1/2/3, plus I love mountains, skiing, and gaming - so I'm probably their ideal customer. For me it's around an 8/9 out of 10.