It's easy to use, it has great community features (like an active Slack channel), there are lots of ways to pay for events, you can integrate with your own apps or services if needed, and I love that they're open source! The only thing is that sometimes people don't have time/aren't interested in attending their local meetups so we end up not having enough attenders at our monthly meetings - which makes me feel bad about running them because then no one comes either :). We've been using doceo as part of organizing workshops where participants give presentations to each other over video chat.