It's about as good as not having it at all. Check out Chrome's _usable_ implementation, where I have such a breakthrough (and apparently insurmountable for Mozilla) feature as conveniently switching between profiles.
Wow, is it really that difficult to click "launch profile in a new browser"? I mean I know we're all becoming spoiled brats over time, but to consider a click or two "unusable" is truly beyond the pale.