Joel Spolsky has a nice examination of why exactly the fonts look so weird on the Windows beta of Safari 3 or at least the technical reasons behind the font rendering looking so odd on Windows boxen. I'll admit that it was the first thing I noticed when I installed it on one of my work machines. To me, it looked less blurry than a little bit on the greasy side, like the 'ink' had saturated through the surface of the window and pixel hinted by soaking in. Yeah, I know, that does sound like an idiot's description of what it looks like but that is the reason I'm linking to Joel's post.
I think what really makes it fail in terms of seeming like a native Windows application is that it looks completely different and doesn't behave like a MSFT application. Try resizing the application and you'll notice it immediately. I dunno whether this will improve in future versions (one would hope that it would before it hits an actual release but we are talking about sleeping with the enemy here) and that some of holes caused by the cross-platform port will be addressed as well. I'm not sure that it will be the expected coup that Apple anticipated. Shit, I spend the majority of my time on an Apple machine these days and I use Safari for testing only.