Difficulties: On Mastodon I had two accounts on different instances. It took some some to decide which to keep and which to deactivate. Not a big problem, as I am not a very active user.
I’ve been using Lemmy since the early days. It was harder to choose an instance on Lemmy than Mastodon.
I have never managed to find a PeerTube instance that I could use for uploading.
So, main difficulty would be time spent lookin for instances.
Challenges: I have never really spent time trying to attract users. When describing it to some people they liked the idea, but wouldn’t move to a social network where their friends were not.
Experience: Positive overall. I have had exactly one confusing problem with another user. I will say that there are some strongly opinionated people on Fedi. Instances do create groupthink which can lead to biases, but I was aware of that before onboarding.
Feedback: The Fediverse is a good social network for many different people. It appears to me that Fedi can be quite welcoming to neurodivergent and LGBTQ+ communities. There is a political leaning, at least on the instances I see. I wouldn’t say there is a slant, but when opposing opinions collide, wording matters because #FediBlock is a thing. I am of the opinion that improvement should come about organically. Forcing changes is pointless, unless you are a developer who can suggest a way to make the improvement a reality.
New users to Mastodon (and Fedi as a whole) need to understand that “quote-tooting” isn’t a thing, monetisation isn’t a goal, and it will never be a 1:1 clone of Twitter, Reddit or Instagram.