One of the major complaints I see is similar to complaints over the Fediverse: that it's an echo chamber. Unfortunately, I'd have to agree to some extent. It's hard to find content variety here. Unless you're hardcore into Bitcoin and libertarian philosophies, you're going to struggle to find people to interact with. I respect Bitcoin (and would love to get into it, if I could) and I have a few libertarian beliefs, but even I end up finding more conflict than I'd like.
If we want Nostr to succeed, we need more people posting with a lot more variety.