The home key issue is the biggest annoyance for me. I was trying the Aviate launcher and it made it almost unusable.
Many people are reporting Bluetooth issues, particularly after the upgrade with existing devices. Sometimes unpairing and reestablishing the pair fixes the problem. I've done a factory reset and that seems to have fixed almost everything.
I concur about the battery. At best it is the same as before, but it's usually a bit worse - as much as an extra 1% per hour of drain compared with before. It was the same both before and after the factory reset that I did. It may have something to do with Google Play Services - I'm still waiting for the update. But I probably received the last, buggy update right around the time that I updated to KitKat last month. What's weird is that it isn't consistent - some days I end up with 40% battery, some days I end up with 60%, and usage is the same.
The only Play Store issues I've had came after the factory data reset - it took hours to reinstall all of my apps. Otherwise that's been rock-solid for me.