I had the beachball issue at initial setup. It was during the Filevault setup (which I had never seen before during a Mac setup, so that was weird in and of itself).
That said, it was definitely a pain to handle. I restarted the machine but then it forced me to create a new profile and it was telling me I couldn't use my name for the machine because it was already taken. This time around it didn't bother asking me about Filevault and finally started up the OS. From there, I had to log out of the new profile and login to the original name I created. Then I deleted the second profile I had setup.
From there, because my iCloud has a million things going on, Apple doesn't do a good job letting you know that there are a lot of background processes going on. So I would beachball here and there as photos and mail and other things were getting setup.
Finally after a couple hours, things settled down and now the machine works perfectly. But I do think Apple needs to better figure out the initial setup process.