Some of the reactions from conventional gamers and the usual anti-VR crowd have been pretty bizarre. One guy actually threatened to start a class-action lawsuit since he felt Valve was locking out gamers by making the game VR only.
There have also been a lot of posts bemoaning the fact that in addition to needing a VR headset, you'll probably have to upgrade your PC. While the hardware requirements for the game seem reasonable to me I don't see how that's different from newer games just needing more powerful hardware to run properly.
Personally, I hope Valve sticks to its guns and keeps Half Life: Alyx VR only. Maybe a full on VR exclusive entry in a beloved gaming franchise will get more people to actually give VR a try.