I don't even open the app and i always get a message in the watch saying spotify is draining my battery press "fix now" to close the app.
I got Spotify Premium yesterday and have been trying out the app. Here's what I've found so far.
Today I opened the app and downloaded some playlists before going out running. I got this message just before I started Samsung Health, so I pressed "fix now" thinking it would just close the app My watch went into cool down mode and I had to restart it. After the restart everything worked fine.
Normally when I run with GPS, LTE, continuous heart rate monitoring, and music playing (on BT headphones) from local storage, I lose 5% battery life per ten minutes. With Spotify streaming my music via LTE, It's more like 10% every ten minutes. Compare this with about 1% per ten minutes when I jog on a treadmill with my phone nearby, and only use heart rate monitoring. Clearly the bulk of the power was generally being taken up by some combination of Bluetooth, GPS, and music playback from my watch. But streaming over LTE seems to add a fair bit.
I also tried running on a treadmill with just bluetooth headphones and Spotify LTE streaming. This was about 6% per ten minutes. So not having GPS enabled seems to account for about half of the battery drain.
I not yet checked what the discharge rate would be like if if I download music rather than stream, but this will be my next experiment.