It may have been, but it was dropped on the floor, which happened after Mac OS was using it as the default browser as part of their 1997 deal with Microsoft, to be replaced with Safari in 2003 - pretty late IMHO.
This year's technical excellence can be next year's pain in the ass, as seen with IExplorer. And I don't understand why they haven't open-sourced IExplorer yet.
Shame it was dropped. I am not sure many people would use it now on Mac, given its less than stellar reputation on Windows (although possibly this reputation only exists in nerdy circles and not with the average "normal" computer user).
Safari has always been mostly OK on the Mac (although I tend to use Chromium instead) but on the iPad it crashes a lot for me.
It always makes me laugh the shouts of "NOO!!!" and general disbelief at the Mac conference when IE was announced. The sky was falling. It fell and became glossy and shiny and Apple lives.