When I’ve used it, gapless playback being non-existent due to it basically being a frontend to the web client/MusicKit for web. I listen to a lot of albums in full nowadays, so that can really hurt the experience. It’s a shame because everything else about it is great. I am aware that the Cider devs are trying to find ways of handling that without reliance on the web client/API, which might enable gapless but also stuff like lossless if you got AM for that.
Edit: I should mention that Cider has a new client that’s paid but still supports Linux (specifically with AppImage, .deb and .rpm packages), and my experience was with Cider Classic.
Edit 2: I bought Cider 2 and so far it’s working well. You sacrifice lossless and maybe some gapless playback still, but it’s a mild loss vs. so far a huge gain in usability.