Thank you, I already read the change logs. I was more interested in finding out what users and admins personally thought were the best or most important improvement out of these long lists of changes.
IMHO Nop-Templates blogs are a good summary of the most important improvements. Nevertheless you have to consider the particular needs of your client. Maybe, as an example, there was a big improvement in Blog features but is irrelevant for your client, since he doesn't have a blog.
You also have to check new plugins and extensions in the Nop marketplace that are only available for these new versions