This beta is very nice overall. It's noticeably faster than any other browser I've tried. I know that speed is very difficult to measure, but I put this through a SunSpider Javascript benchmark test along with a pre-release build of Camino 2 (same Gecko branch as Firefox 3.0.x) and the latest beta of Firefox 3.1. Safari 4 came up over 3.5 times faster than Camino and over 1.5 times faster than Firefox. It also achieves 100 on the Acid 3 Test.

The interface is lovely--minimal and functional. I'm undecided on the tabs at the top of the screen, but one con is that I keep accidentally moving the window when I want to drag a tab. Sadly, Safari still lacks single-window mode (though it's still available as a hidden preference) and session saving. Fortunately, Glims was updated quickly to work with version 4, filling in these two gaps (among others). Another essential add-on, the current beta of 1Password is compatible. I also recommend the Click-to-Flash WebKit plugin and GlimmerBlocker proxy ad blocker for anyone interested in content blocking. Neither of these involve input managers and both work perfectly well with Safari 4.