Sadly I don't own a N5
My N4 is running it though but I gave that to the parents, So I have to wait for my HTC one to get it hopefully by the end of the week. Good to see theme engine has been put in, I just hope they don't disband per app colour completely.
The thing I liked about halo is I could set up some apps in the halo app & quick swipe the bubble & have another app open straight away in floating mode, With Hover there isn't any option to do this apart from a active notification by long pressing i t & selecting floating mode.
I used it a hell of a lot for multitasking more than the notification side of things. But I definitely like how they are styling things in these betas it is how I would expect Google to kinda do it.
Either way I wouldn't change from PA it has always been the most stable ROM for me, I don't like all kinds of clutter kinda how PACrom is although it is nice a ROM. Its more for people who likes to enjoy lots of options.