zlacker

As a person who habitualy closes everything, I often average around 5 tabs open, rarely going above 10. With so few open at a time, the giant column of vertical space for the tab tree would be a waste of screen real estate, which can be better utilized to open another window i a vertical split arangement, or just for the website's content. Having said that, I know one of my friends has always at minimum 100 tabs open at any time, so he jumped at this feature as soon as ut released. It's a matter of preference I'd say.

>>kdklol+(OP)
I'm the same. In the rare case I do have a lot of tabs open it tends to be a queue that I work through in order anyways so having them not fit on screen isn't a problem. My theory is that once I get over 20 tabs or so it will be quicker to just re-open the document (just type a few words in the URL bar and history-search will find it) than actually locate and click it. I'm glad that Firefox is flexible enough for tab hoarders and tab closers. Having a horizontal tab bar that doesn't take up too much space is perfect for me.

>>kdklol+(OP)
The benefit of vertical tabs is (IMO) more about organization than having tons of tabs open. It's particularly useful to have a tree of tabs when browsing API documentation, to allow for quickly navigating to different doc pages in the hierarchy without having to wait for page loads.