Great to get some feedback from someone who’s tried it! I looked into SofR at one point in late 2019, just an itch to want to be in a band, from finishing B2B, doing some covers, and wanting to try out my bass playing in the real world, or, at least the semi-real world!
From inquiring with the local SofR, it did seem like most of their business came from an under 18 crowd, but they did mention adult classes, where they match you up with other adults - hopefully a drummer and a guitarist, so you can start getting a feel for what jamming and such will be like. What I liked about it was that it seemed nicely structured, and, you wouldn’t run into flakiness, since, well, people were paying to be in it.
I was close to doing it, but tried my luck at the time instead on random Craigslist bands that needed a bass player. No regrets, but there’s no structure to that, and, people that you run into can be very hit or miss. Still, it worked for me, and there’s some freedom from all sides to doing it that way. Sometimes you just don’t gel with people you meet, or they with you, or other issues that crop up. But it does take some work to figure it all out, and, SofR seems like a good option to bypass some of that, as well as the beginner-friendliness of it!