とりあえず、入れておけば他のブラウザやFirefox自体のプロファイルの使い分けを減らせるので便利です。
欲を言うと、次のような機能があったらいいなと思います。
・メニュー上のコンテナを任意の順序に並び替え
・ステータスバーから新規タブを開く際のコンテナ選択をするかしないかの設定
・タブやページの標準コンテキストメニューでコンテナの移動やコンテナ別新規タブのオープン

更に欲を言うと、タブリストボードのようなタブの一覧をグループ化して表示するアドオンやセッションマネージャーと一体化し、一覧ページ内でコンテナ別に表示して、まとめてブックマーク、まとめて閉じる、以前開いていたタブをセッション付きで復元と言った操作を簡単に行えたら最高ですね。

Fairly good, and certainly an improvement over one of the few features that kept me on Chromium/Chrome until now. Being able to sand box tabs is quite useful for the sites (social media) where I have multiple accounts, now I needn't log out/log in to use them, and it even helps with sharing.

Hopefully we'll see improvements in the future, I for one would like to see more control over the default container, and would like an easier way to select the container than the current button/list (ctrl+c1/ctrl+c2 perhaps?).

EDIT 3 NOV
Still liking this, but seeing one area that could use to be improved, it'd prolly be a good thing if the highlights section of a new tab was restricted to content previously seen in that container.

I really appreciate this extension! However, some essential features I am missing include:
* Ability to sync settings. I've recently found myself having to delete and recreate profiles to no end, troubleshooting an issue with another extension. Reassigning my banking sites to the banking container, my email to personal, etc., etc. is fun the first time, tedious the 3rd, and frustrating past that.
* Ability to automatically open a site in another container. For example, I forget to FIRST select that I want a certain container, I just go to the site. Oops. Now I have to open the correct container, then go copy the URL and paste it in. Would be great if we could right-click and "reopen" in or "move" to a different container.

I'm certain I gave feedback on the first one some time ago somewhere, but can't find where that was to follow up. (email? Twitter?) I'm finding myself about to recreate a FF profile again, and even just being able to save my current settings and then manually reapply them would be a good workaround at this point...

wow love wish i had this yr's A GO NOW I HAVE ms. it,s slow me down i well tell all i can and tell to pass it on if was old man that fell in a gold mine make fell like landing Down cry Tell All FireFOX is the way to go

Tab hoarders unite! (I'm pretty sure that because of the multi-account component, this isn't what the original creators thought would be its use but hey, it works great for it as well)

I honestly love this extension, but I couldn't give it that last star. There's two or three things I would love to see updated for containers that would definitely earn that last star though: switching a tab to new containers from either no container or a different container (one at a time or en masse), as this would allow first time container users who hoard tabs to move them over a little more easily; the ability to shift around containers (i.e. move up a container that's in constant use up, or move one that I don't really care for down), as currently the only way to "move" them is by deleting the container and then making it again which puts it at the bottom of the list; and if you could make it so that tabs in a closed container (or open for that matter) would sync with firefox sync (and the containers themselves!). These changes are the only things getting in the way of this being from my perspective the ultimate tab sorter.

Containers has honestly helped me organize my online activity and helped me put my distractions into a side tab, though; so I honestly say this is one of, if not the, best add-on on Firefox, which is (in my incredibly biased and tab-hoarding opinion) the best internet browser.

great i have multiple login in one site. Can open different container and login without leaving the browser

It's a nice step toward having different personality/user profiles for the same installation of Firefox.

Love it! What I'd like to see:
- ability to sync containers (with open tabs) across devices
- or: add container info to synced tabs if possible, which would accomplish the same as above
- ability to choose which container to use when clicking the "+" button in the tab-bar

Works very well. Can be fiddly opening sites into new containers but can be set up to work smoothly and automatically once you do so.

This has been something a long time needed. The biggest issue is in overall usability. The process of assigning a tab (especially one already open) needs to be streamlined. Still, it does exactly what it claims to do, and does it well.

Love using this to help keep some semblance of separation between different activities tracking you, especially facebook and amazon. Only thing missing is that it doesn't synchronize across browsers, so I have to re-create the containers and web sites on different machines.

Very useful! Though needs better control of settings and easier ways to open tabs in the desired container, switch containers for a tab, etc.. Clunky to add sites one at a time. And desperately needs more granularity: for example, I want Google Maps to open in a separate container than Google Search.

Why I can't change the current tab to a group... that's the only issue.

amazing! reason why i haven't switched to chrome because of mozilla's focus on privacy. one star removed because this addon should be syncing in the first place with firefox sync so whenever i access firefox in my other devices, the containers i setup should be synced.

Good & Useful.
Looks like Multi-Account + Tab Groups . & developed by Mozilla make me feel better than thirdparty .

But . If when I use this addon as Tab Groups .
It 's very inconvenient to change which container I want show only.
It will be better has a button on [container list] that I can make one be only show.
& even which 2 or more container to show or hide.
need it not go into the [tab list] to set it hide or show than come out one by one..

Now this addon do good job on Multi-Account .
But the TabHiding function is completely wasted cuz extremely inconvenient to use .

The reason I didn't give Containers 5 stars is because I can't Clear History per container, but rather have to delete a container and recreate it. Support for removing history per container seems to be already in the WebExtenions API.

Great idea, with a sleek user-friendly, intuitive execution. I found it easy to open, manage and use different containers. One missing feature that I've felt is the ability to process histories/cache's etc. within each container. e.g. "delete all history from container [shopping], but keep the other container data".
Otherwise, it's a useful add-on that helps users manage and understand their online footprint. Thanks for making it!

Missing two main features: picking RGB colors and switching containers.

Great to split personal and work or if you need to access same service from several distinct accounts like Google services. As Mettarefuge sayed, it would be nice to have more colors (good idea for the input).

Great job. But can we have a more options for the colors? Maybe an input for RGB codes or a color picker. It would be nice :)

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.