They have hundreds of thousands of units out, developers of all sizes working on content, and an enthusiastic (and paying) community of users. That's a pretty good launch for a new consumer tech category.
Then the devices came out, and you hear nothing anymore. Sure, there are a bunch of people who bought it, but when none of the vendors are even releasing sales figures, you know it's disappointing. With the recent news that Oculus is closing their demo stations because no one is using them suggests that things aren't going too well.
VR is probably not as bad as 3D TV in terms of a flop, but I don't think anyone can call it a "success" unless your expectations are very different from that of most people.
https://www.cnet.com/news/vr-disappoints-at-ces-2017-lenovo-...
Selling hundreds of thousands of $800 units is $80M in revenue, not a bad start for a new technology starting out in the "consumer goods, luxury entertainment" market.