I mean, I hope things go well for them and their partnership brings nothing but good things. From what I've seen, they've put a lot of work in to their device and made significant gains. But Facebook doesn't and won't have a device in my life, and I refuse to buy an Occulus product because I don't believe that Facebook won't get access to usage data (or be involved as a platform middleman).
Oculus complete source code is available. That still doesn't guarantee their transparency; I'm certain when the next version( when under Facebook ) is released it won't have any facebook integration, and its protocols will be checked and revealed by the community anyway.
That doesn't necessarily mean anything. Lots of hip tech companies open source a lot of things, that doesn't make their rent-seeking, dark-patterned, scammy operations any better for the end consumer.
Facebook is one of those companies who's done so much public bad that I personally can never forgive them - it doesn't matter if they open source Oculus code, I just simply will not participate in anything that will make Facebook richer.