Setup v8.x on dev environment and cannot get accustomed to the modified Admin area layout...I am normally not excited about big changes, but have always quickly acclimated to other change in short order.
I spend too many hours of my life in previous WHMCS admin, and am having no such luck with 8 so I am going to wait it out before making any changes to production site. Aside from the layout, no other significant issues arose during my test upgrade...It would be the smoothest WHMCS major release upgrade in the history of our business if we were able to replicate the same results as our test-run.
Normally, maintenance mode and 5-10 minutes of hastily going back and forth to error logs accompany any major update. Sadly, we may never experience.