It's one of the design decision that OmniGroup has expressed where they stand and it seems to be love it or hate it. I'm curious if it will change in OS X 10.4.5 because from what I've heard, drawers aren't going to be supported or something, so a change may have to happen.
My only issue is that the tabs require the user to expand the amount of real estate the browser window takes up. I would love to see an integrated sidebar -inside- the window that lets you look at your bookmarks, history, downloads, and tabs, somewhat like Shiira does. At the very least, I think integrating the tab display into the window such that you don't need to resize your window every time you want to see your tabs would solve a lot of the problems.
Anywho, yeah, this subject has been discussed ad nauseam, and it's one of those things that if it's a deal breaker to you, it's not worth purchasing the software.
I will admit though, as much as I like graphical tabs, there are times when I -really- miss having a tab bar, and I would love to have the option of either or.