Just my opinion but it's really not that major. Our office uses Lion's addressbook everyday to search for clients and colleague contacts and not a single person has complained since moving from Snow Leopard. The only thing that was acknowledged was the UI change. A few people said, "Oh, it looks more like the iPad Addressbook now". That's all.
The mini month is there, in fact I like the way they offer it now than Snow Leopard's iCal. I will agree it wasn't obvious because I didn't use my daily calendar much but that's where it is. Now I find myself using the Daily calendar because it shows the existing mini month plus all of our office appointments for the next several months. I find no need to switch to month view anymore. IMO the new iCal is more convenient.
I think the people here are being silly screaming about the new leather-like look.

. It's just a calendar and addressbook. It's not like the menu bar was changed to leather.
I did say earlier that Apple needs to work on Expose' more and that App Expose should be a part of MC. I don't think they did a perfect job with that either but it doesn't mess up my daily workflow. Again just my opinion but I think this has been so blown out of proportion here. If people are really "using" their Macs they should be dove into the app they are using, not constantly playing with Expose all day. It's just to help you find a window and move on.