I have been using it for a bit since yesternight, so far I like it although I still kind of have to get used to it (I have been out of the habit of microblogging for like 6 or 7 years).
The UI is actually quite nice, with pretty good looking themes. There is a distinction between "global" (known network), "local" (your instance), and "social" (mostly people you follow), as well as "recommended" timelines. Features like channels I might explore some time in the future, so currently cannot say much about them.
Onboarding works quite nice with how you are being guided through filling in a profile, selecting a first few people to follow and writing a first post.
My Lemmy profile page shows my Calckey account, for those of you who wish to follow me. π