It's superb. It's a drop-in replacement for `docker build` on my M1 Macbook and on GitHub Actions. I really like that they use OIDC for auth in the latter, so I don't have to provision credentials. Of course I also like that builds are 3-4x faster.
I have to admit though that the pricing model doesn't make a whole lot of sense to me. It's $25/mo/project, but what's to stop me from using one project for multiple, unrelated Docker images? It's a relatively small cost for saving me time, but it's still big enough that I have slight hesitation to spin up more projects.