I hope they just make it part of the standard release.
no nested tabs :/ it looks like a toy plugin compared to TST
I've been pretty happy with Tab Center too. Tab handling is the one thing a browser has to nail for me and yet so many (including base firefox) do such a poor job of it.
checkout "tabs outliner" on chrome.
I've tried it and it's just so clumsy I couldn't really use it.