The most difficult part so far has been finding communities and joining them.
It's difficult to search for communities that aren't on your home instance.
If you go to a big instance and search for communities there, you can't directly join them, but have to go back to your home instance and paste something into a specific field, then click "next" since the community is never the first result, then click on the community to load it up in your home instance and THEN join it.
Communities are fractured across instances - I found at least five different serves with a "cat" / "cats" communities, and there's no way to aggregate these, and it's difficult to search out the rest of the cat content without just going to the other instance servers one-by-one and doing it manually