Not just including apps but here's the welcome changes I've found:
Cortana
Live Folders
Lumia Camera 5 (will be testing the higher HD video settings soon)
Calender doesn't display old latin garbled text when you view the month
Gestures beta
Netflix app now has a live tile
ProShot (was this available with 8.0? just got it)
Live lockscreen beta was fun for an afternoon and it'll be great once it's optimized, currently it's too slow for me to bring up the screen but it was pretty
I hear the VLC player beta was worse than it's pc app beta, near unusable. But once that's been worked out and public I can't wait to try it.
Downsides: Anything media
music app doubled all my playlists as it was pulling the list from the cloud and the phone
music app will show album art and artist art sometimes but only when viewing the song, never on the live tile or the lockscreen like in 8.0
Podcasts disappeared and the native podcast app doesn't work and crashes 1-2 seconds after opening each time