Android N has made some significant, nay, major changes to the notification cards compared to the outgoing L. For one, notifications now just look a lot more same-y: your Hangouts notifications don't look much different than your Inbox notifications which don't look much different from your Gmail notifications and so on and so forth. Small icons, little border separating individual cards, and a whole lot of white space can make Android N's notifications more difficult to visually parse, particularly if you're getting a huge number of notifications.
The collapsible notifications - aka bundling - are also something of a mess at the moment. Some apps basically don't use them at all, and some apps like Gmail use them a little too much, allowing you up to three levels of collapsibility for a single Gmail notification card.
A lot of this depends on how you deal with notifications and how many notifications you receive in a day. Aside from my Android Police email, I don't get terribly many - I keep my devices notification-light expressly because I abhor notification spam, i.e. Facebook telling me it's someone's birthday that I've not spoken to in six years and who now exclusively posts Trump videos. Thanks, Facebook.
Anyway, have the changes in Android N been to your liking? Disliking? Personally, I'm kind of ambivalent on this one - I don't hate the new notification cards, and I don't absolutely find myself absolutely loving them (apart from the new convo view quick reply mode as seen in Messenger).