General

It's different. I wish I had the ability to create a meta-community (or meta-instance) that pulls communities from different instances together into one feed without having to mass-subscribe to all of them.

The fact there are multiple communities of the same or similar interest spread across multiple instances makes it much harder to get a good grasp of actual activity, so it takes more effort to reach a critical mass.

It'll get better with time since Lemmy is still pretty underdeveloped as software.

It's pretty slow on activity. My most visited sub garners only 5% of the action it had on Reddit. Lemmy also doesn't have my niche subs.

Hard to say. Burggit was defederated so quickly that I never really got to make use of the other instances. As it is now this instance could almost just be another message board. Don't know if there's any chance of re-federation once moderation tools improve. I hope so. I do like the communities feature of Lemmy. They provide a gathering place that was missing in Mastodon.