I am not a fan of the Remote app because it is so limited with Apple Music. It should take some notes from Spotify at this point.Good stuff. The buffering improvements are very welcome. I gave up on using Airport Express because of this. My Yamaha receiver does better, and has intelligent volume control unlike the lossy control you get with AE.
Instant Play/Pause/Skip is very nice too. Hopefully we can get control from lock screens. It takes too long to unlock, open Remote app, etc. if you need to pause the music. And speaking of the remote app it really needs some help too. We lost artist names from the "Album" view a while back, and it would be nice to have a "recently added" section similar to the Music app. I've been trying out Teamviewer to remote control my music PC instead of the Remote app because the remote app is so behind.
My APEs have always worked great. My main issues were with a Phillips Soundring Speaker wanting to be the same IP Addess as some stuff already on the network. Even when I fixed it, a power outage would screw everything up again. I now just use the speaker for its aux connection with my Echo Dot and it powers the iPad in the kitchen with its USB port. The only time I use it for Airplay is when I want to test something like multiroom audio because it is close enough to the living room that I can hear any sync problems from the couch.