I've migrated my Boost builds from Travis and Appveyor to your CI offering recently. It wasn't super smooth, but I got it to work quite fast and I like it a lot.

So sure, I'm missing caching that I've had on Travis. But honestly, it builds reliably fast anyway. On Travis, I always needed to wait a LONG time to get macOS agents, on Appveyor, we were limited to 2 parallel builds. Here, everything starts all at once, completes under 10 minutes (there's quite a lot to build and test).

If I could, I would love to have an sccache ( https://github.com/mozilla/sccache ) compatible distributed free caching solution for my C++ projects. That'd be a killer feature!