L-flavored apps working just fine on this ROM:
Play and Play Services. Had problems with side-loaded Play from the thread, but the versions auto-updated by Google are working without a hitch.
Calendar. Remove older version first, whether from the ROM or from Play, then side-load version from the thread. New material interface, event view. Other views accessible from the upper-right menu and elsewhere. Caveat: Much larger than previous versions--must install as user app on our device.
Messenger. No new functionality, but with material UI. Hint: Make it the default message handler. LIke this one? The mms from the ROM can be removed. Hangouts2 is another alternative, of course.
GMail5. Official (but leaked) apk installs normally (user App) and runs out of the box. Will handle non-gmail accounts as well. Material interface. Version on thread from preview image was laggy. This one is fine. I have been happily using K-9 for a couple of years, but may go over the gmail5 since it can handle all my accounts, nicer interface.
What won't work: Keyboard, Camera -- depend on prebuilt armv7 libs--old news. Dialer and contacts -- depend on newer API.
Boo-hiss: Microsoft has a lovely lockscreen and OneNote app, but these come with prebuilt armv7 libs.