From my experience, as everyone said, it does depend on so many factors.
For me, when it's room scale VR, I tend to not get sick, as long as the tracking actually follows me (Played a bunch of Robo Recall, it's just amazing!), but then, I've had about 100h in a VR headset, mostly Oculus Rift CV1, on high end PCs that have no issue running the games at 90FPS steadily.
During my testing days, the simplest hitch and dip in FPS would make me sick right away. A good tool to help ease the motion sickness is Ginger Ale (like Canada Dry). The ginger and the bubbles help steady the stomach.
And then, like so many said, some games are comfortable in the way they are designed, some are not. Even though I'm used to VR, I can't play lucky's tale. I just get sick in about 5 minutes. Something with the way the movement is handled.
Overall, it's different for everyone. Some people can't bare not seeing what is around them, and therefore simply can't use VR, some others get sick quickly, some others don't. You do get used to it, I think, but you have to see if the process of getting used to it is worth it (IMO, it definitely is!). It's definitely a try before you buy thing, where you should try it on a system as close to what you will have as you can.