I use it to follow people who either have ideas I find interesting or do stuff I find interesting, and typically I'm looking for accounts that are small enough that I know they will at least see my replies, and often interact with them. (Something like 3K-15K followers for most of them, I think.)
I also think it's indispensable for real-time commentary and niche commentary on current events: always requires grains of salt but there's just no better place on the Internet for that sort of thing, in part because...
It's the one major social network I'm on where it is easy to view only posts from the people I follow, in reverse chronological order. A feed I TRULY control (and, if you follow the right people, insulates you from much of the nonsense on the site).
And every once in awhile, some insane viral nonsense pokes in that makes you say "how could I ever quit this site". There's a certain genre of satirical accounts that is very entertaining as well. Definitely a guilty pleasure component to it all!
>Is it still as popular as it used to be?
A quick search roughly aligns with my perception: it bottomed out a couple of years ago and has gradually recovered, though not to where it was pre-X.