This is my experience with Discover Weekly as well. Everyone seems to be really divided on how well their algorithms work, they either work really well or terribly. I think it's because the quality of signals their algorithm can key off of is so limited due to it being such a passive medium.

There's no way to know if I listened to that track in full because I liked it or because I had it on in the background while doing other work and it wasn't distracting enough (usually the latter is the case for me). Furthermore if I skip a track they don't know if I skipped it because I didn't like it or I wasn't in the mood for that style of music, or I was just sick of that song cause I've heard it enough in the past X listens.

There's no way to easily signal to spotify why I'm taking an action, and yet their algorithms are trying to make assumptions over every little action.