I've been trying Spotify out for podcasts to replace Google podcasts. I had a mental block at first, thinking of Spotify as anything other than a "music" app, but, now that I've broken that block - I like it.
Regarding courses though - I'm not so sure. I think projects, homework, and interaction (e.g. with fellow students and instructors) are a big part of learning. I'll definitely check it out, and I hope Spotify delivers something good, but I'm a bit skeptical at the moment.