Good

This is a game changer. I loved Firefox in the past, but really had trouble coming back. The containers are amazing for many of us concerned about privacy, security, and organizing our online lives. These have made Firefox, once again, my go-to browser.

Definitely one of the indispensable extensions if you have multiple accounts on some sites like me. It works exactly as expected, fast and elegantly designed. If there’s one minor thing I still wish, it’d be showing in history which container each entry belonged to.

Great addon for those who need to access same service from several distinct accounts. (e.g. Google developer console)

My favorite part of Firefox!

Very good modulen, needed for an enjoyable web experience.
The only thing missing IMO is that we cannot change the current tab's container.

This is very helpful. My only complaint, it that when I have many tabs and then click on the dropdown arrow, the listing does not show the colors of the contains for each site like it does when the tabs are visible.

I've really come to depend on the multi-account containers. It's a much better alternative to using profiles for managing online accounts.

@Albert Kolkin:
I use it with multiple gmail accounts. The secret is to press and hold the "+" button so that you can select the container that you want to use. Then you can go to gmail.com using a bookmark for example. Since there is only one url for accessing gmail you can't use the always open the bookmark in a particular container feature like you were trying to do.

Una maravilla de extension, antes tenia que abrir diferentes navegadores, ventanas en modo en incognito pero ahora con esta no hay necesidad de eso, ya no tengo que salir de mi amado Firefox

works great for me! i just wish there was more color options for separating specific sites, like not having Ebay and Amazon on the same shopping container, but a separate one which can be recognized by a separate color

Sorry, it does not work as I thought it was supposed to.
I installed it.
I have as one of my home pages a gmail work account. I assign it to Work, click on always load into work. When I restart Firefox Nightly it has not opened it in the Work container.
I tried setting the work container as part of the home pages, but that did not work either.
I do not know whether it is Nightly or some other problem. Both google emails accounts open correctly, but neither is separated from the other by category.

Now, after removing the add-on, When started Firefox Nightly yet again, I got a dialog that asked me into which container did I want to load the tab, and whether or not I wanted to load it into that container always. I would have given it a lot higher rating but for this strange "feature"

Awesome plugin. Thanks for thinking out of the box!

This, combined with Cookie AutoDelete is fanastic. I can keep suspicious sites (and services) isolated from things I care about. With Cookie AutoDelete, cookies I don't want are erased when I close the container. It is a lot like "private browsing" or using Focus on a cell phone / iPad with some advantages. Login cookies can stay alive until I totally close the browser.

Highly, highly recommended.

This app along with the profile options (firefox -P) make the ultimate combination for privacy oriented people.

Keep up the good work Mozilla.

It's one of these things that you didn't know that they exist but now you can't imagine your life without them. It will make you feel pity for your former self. No more logging in multiple browsers to handle multiple accounts on the same domain.

Really useful while developing sites which needs backend and frontend tests with separated cookies, sessions, etc, separated.

It works as intended but it's annoying when I click a link to an outside site and it still opens in the current type of container. The facebook container standalone add-on breaks out of the container when clicking links to an external site, so it's strange that this add-on doesn't have that function.

This is the primary reason for why I prefer Firefox

I used to use seperate browsers for different activities but now Firefox is my only browser. So in many ways, these containers have made my browsing a lot simpler.

The initial version of containers was very limited, but then it's like they took all my feedback and implemented it exactly the way I wanted. It's great for logging into multiple google accounts at one time, while being able to use all their other services seamlessly. You can also create named containers ones which is what I was really missing at first and it is easy to tell which tabs are in which containers.