Why? It feels faster and the middle button of my Microsoft Intellimouse Explorer Optical mouse works for popping new windows or tabs. But I will probably switch to Firefox as my default browser when it goes 1.0 because it just keeps getting faster and I doubt Safari can catch up!
Ironically, although Microsoft cited competition with Apple’s Safari as the reason for killing IE for the Mac, I’ve abandoned Safari on OS X for the same reason I’ve abandoned IE on Windows. Firefox does more, it’s moving faster, and — here’s the kicker — it runs identically on Windows, OS X, and Linux.