Very buggy and misses important features.
Firstly: If you open a page in the incorrect container there is no way to easily reopen the page in a different container.
Always opening a page in a specific container is an option that is only presented when you have already opened the page in that specific container.
Even after asigning a page to a specific container, if for example you open such a page from a different container you will be presented with an interface to pick whether you want to open in default container or the current one. There is a "do not ask again" option but it doesn't function at all. You are always asked.
There is no administration page, no settings, no nothing. The only "option" is to remember the assigned container after you have already opened the page in the container, and, like I said, that feature DOESN't work well.
Containers also break some functionality. If you have facebook in container A and want to use facebook for login on a site on container B, this will not work.
This addon had the pottential to be a great feature but it's awfully implemented.