It works great, except for the part where it can potentially cause data loss (switching a tab to or from the Facebook Container, e.g. by visiting Facebook.com from a Google.com search, causes the tab's navigation history to be discarded)
Note: it doesn't break your history menu or anything; as long as you don't clear your history, you should be able to get back to where you were by digging through that. However, it's quite tedious and for some people, Multi-Account Containers might be a better choice.