In the trailer the interaction with objects seem to be too smooth.
That part where Alex reaches for shotgun shells behind some cans seems quite unrealistic, I do not think this is actual gameplay.
When I watch VR gameplay the hand/guns usually have tremors, they are rarely smooth.
I am quite sceptical that VR for PC will ever become mainstream. Nobody will devote enough budget to make a AAA game where only a small portion of user-base actually has VR set.
HL:A will surely boost VR adoption but financially, I do not think it will be successful and I do not think that other companies will begin to set aside large budgets for VR games.
I absolutely loved HL1 and HL2, I was close to buying £1000 valve index but then I looked at other games available and none of them look particularly interesting to me.
If there were more games with AAA budget, story and full length 8+ hours of gameplay then it could be interesting but there are so few if any of them out. Most of it is just stand and shoot.
I want this game to be successful but I think it will be another failure for valve, they seem to have lost their touch with failed projects such as steam machines, controller, artefact.