The biggest thing I'm hoping is fixed on watchOS is the bugs with the Podcast app - currently it often doesn't show the latest episode available even though it will begin to play the latest episode if you go to the end of the previous episode and let it continue.. it knows it's there but the UI doesn't show it.
Also with the podcast app, it's terrible at 'crossing connection types' - If I start a podcast at home in wifi, then walk out of my house to run.. eventually it will stop playing and any time I try to play a podcast after that, it just stops immediately. I have to reboot the watch to fix it.
My method is disabling wifi on the watch, walking out of my house until it is also no longer paired with the phone and the cellular connection shows up, then start the podcast. Annoying as all hell I can't even tell you.