Rated 4 out of 5 stars
I love the idea of vetical tabs and used to use sidetabs a lot (although I feel like it was buggy). Vertical tabs seems like the next rev. I'm a fan even though I find the re-ordering of tabs a little awkward (it's hard to place a tab just where you want it - try it you'll see.)
Nevertheless, as a person who has 12+ tabs open all the time I think it's much better to have vert. tabs. Thanks much!