It is the Best sidebar I've ever used. The freedom to customize nearly every aspect is superb, and the default configuration is already super lovely and usable.

5.0.0 works flawlessly. ∞/5 all day long.

5.1.1 requires you to turn animations on. neat. 5/5.

Thanks for performance improvements with a lot of tabs in 5.0

i come from treestyletab, and this extension is amazing

I haven't been able to live without vertical tabs in years. This is the best Firefox implementation of it I have found yet.

Just got a big update that improves a bunch of stuff that was already good.

I just discovered that clicking on the tab you're already on switches to the previous one you visited, so repeatedly clicking the same tab switches between the two every click. I have no idea what I'm going to use this feature for, but it feels well designed and I love it.