From 2,997 active users across all lemmy instances at the beginning of June, the number increased to 52,797 by June 30th. Source.
An active user on Lemmy is "someone who has posted or commented on our instance or community within the last given time frame.” Source. That means lurkers are not counted as active users. There are currently almost 200k total users spread across the top 10 non-bot lemmy instances.
We’re really building something here!
EDIT: Looking for a lemmy app? Here’s a whole list: https://lemmy.world/post/465785
Honestly, once apps are improving (though current ones are actually pretty nice) and more users are here - what would I be missing from reddit? Nothing. When I need old content I use Google to get it from reddit, but for anything new there is not a single feature I miss dearly (might be different for moderators).