Chrome's biggest issue on OS X is that it's ugly. Its UI looks like Chrome on Windows and Linux, but not like OS X. The tabs are the wrong shape, the wrong color, and use the wrong font size. The latter two complaints apply equally to the bookmarks bar. At least on my machine (Chrome 18.0.1025 on Mountain Lion), the URL bar is hideous. It's too high, and there is more padding underneath the text than above it, and the focus ring is wrong. While Safari's panels are neutral gray with translucency, Chrome's panels are opaque and stark white. I have tried to use it, but it makes my eyes hurt.
While Mozilla may be slow to implement Apple's new UI features, at least they can paint the UI widgets properly.