There is no need to go to the iCloud Drive usually. Really no need to have it on your Dock, Finder is a more natural place for it.
It is very cool. I have two laptops and an iPhone. iCloud syncs everything in Documents between my laptops. I’m usually reluctant to us sync facilities like this, but it works seamlessly. On the odd occasion where I have done something potentially confusing like open the same file on two laptops it has figured it out.
When you have iCloud activated, you will see that Documents is greyed out in the usual location on Finder, indicating that it’s a synced iCloud location. The only reason you might need to go to the iCloud Drive is that it shows both the iCloud and local versions of Documents, these would normally be in sync.
But the best thing is that I can use the iCloud Drive on my phone to access any file in Documents on my laptop. This has been incredibly useful so many times when I have gone to a meeting where I didn’t think I needed my laptop.