Not sure how to answer a binary option. There are various possibilities depending on the location and the primary demographic attracted to each space. Each space should be appraised on its own. Each one may be beneficial, neutral, detrimental, and a combination of all or none depending on when you show up, if you're part of the organizational clique that runs the space, if you're a visitor with no connection to anyone there and are not wearing the right kind of uniform (or have some other non-standard visual presentation), or if you're looking to get something that you believe is owed to you. Every factor (plus a million I have overlooked) plays into your experience and the experience of others.
Without having visited more than half a dozen, I'm glad they exist. Abstractly, any time radicals can set up (and maintain) a physical location that's regularly available for gathering and meeting, it's a good thing. And like most self-organized projects, what you get out of it will depend on what you put into it.
