[JKT]

I think your preference largely depends on how many tabs you typically have open in a window at any one time. For my style of browsing where I have tens of tabs open at any one time in the same window, the conventional tab model is simply awful. You can't tell what tab is what and anything beyond the e.g. tenth tab is shoved into a pop-up menu and is not remotely easily accessed while the remaining tabs are reduced to useless nothingness in terms of the information they display.

If you only ever have three tabs open in a window then it is OK.

The biggest advantage to me of the vertical tab drawer (other than the visual cue as to what each tab contains which is a given) is that I can use my scroll wheel with it to quickly find tabs that are currently off screen. The second biggest advantage is the visual cue for rearranging tabs to group them. With a conventional tab bar this is nigh on impossible to achieve effectively.