Containers are a good idea. I like the warm-fuzzy of knowing that trackers are limited by Container (right?).
I truly enjoy the color-coding.
And I like the option, accessible from within the little Containers icon* that allows me to choose to group tabs by Container. That Grouping option allows me to keep newly opened tabs together.

However:
1) I need MORE colors. Eight is just not enough.
2)The option to alphabetize Containers by name doesn't flow through to Firefox Settings, and does not alphabetize when adding a new tab.
3) I tried to re-open a Google search tab that was not already in a Container, in a new Container named Amazon, but that operation failed. The new tab opened outside of a Container. The Google search tab opened as expected in a newly created Container named "Research".

I was a little concerned about the privacy of my data given the Containers' permission that says "Store unlimited amount of client-side data", but after reading https://support.mozilla.org/en-US/questions/1265089, that became a non-issue. Thanks!

Firefox is my go-to browser. Thanks for keeping user-privacy and convenience in mind!