This is the must-have feature that keeps me using Firefox -- especially when I'm doing research, which has a naturally tree-like pattern. Apparently, from the Chromium bug, it's a dealbreaker for lots of other people as well: https://code.google.com/p/chromium/issues/detail?id=344870
[1]: https://addons.mozilla.org/en-US/firefox/addon/tree-style-ta...
Another suggestion is to not manage it. I create tabs all the time, and often have many similar tabs. There's no need to manage it, only to clean up once in a while.
(I like many tabs. A few weeks ago I performed some tab-cleaning -- 550 tabs were a bit much, as it made Firefox start slower.)
Personally i just use it for things I would like to read at some point, instead of filling up my bookmarks with 50-10 entries every day.
Disabled that as soon as it was dumped on me. There are an almost infinite list of reasons to have multiple copies of tabs.
Honestly, I cleanup every week or two, and it works fine. Windows are by category of different things I do, and I tend to leave frequent sites open all the time.
I find it essential to manage the mess that is my Chrome tabs.
Panorama is a life-saver if you have to context-switch between projects regularly.
TreeStyle, really, I use more as a means to move screen real-estate to horizontal usage on my laptop's 16:9 screen. Tab organization is a side benefit.