Honestly, it's a barren wasteland, worse than Google+.
As far as I've seen it's mainly used as a replacement for imageboards.
Most of the server topics are either a variant of /b/, or a gathering place for SJWs, furries and lolicons.
As for the people there, the people I talk to are interested in games, philosophy, linux, vaporwave, memes, and meta talk about mastodon and decentralized platforms. There are a lot of trans and and furries and people interested in politics. The vast majority have been unfailingly nice. The granular privacy options allow one to mute those who are overbearing.
And the biggest difference between it and /b/ is that conversations tend to be two-way a lot more. People aren't purposely posting to try and anger you. In fact, here's a post I see on my feed right now:
>someone should write a paper on mastodon as a model of a therapeutic community
If what you're saying is you just don't like platforms that have lots of people you disagree with politically, that's one thing. But the behavior and subject matter and culture are significantly different from /b/ and in no way a wasteland.
If the instances that are not "barren wasteland" are difficult to find, it's a problem.
I actually think this is superior to Twitter model, because you can find an instance that fits your interests closely and not have to deal with the noise you don't care about.
But even if they weren't, the extremely active main instances are enough to show the platform isn't a barren wasteland. And the difficulty of finding offshoot instances with lower amounts of participation is a different category of problem, however real, from the platform itself not having people.