I have been a Chrome user for a couple of years now and I enjoy its quick minimal interface and "everything bar," as well as the advanced syncing features.
But as a Mac user, I've always wanted to take advantage of using Safari as my go-to browser. However, I have always felt that overall it was less productive than Chrome.
That has all changed with the release of Safari for Mountain Lion. The major feature that I have enjoyed so far is the additional of the "everything" bar that allows you to type searches or url's into the same bar. It also will instantly recognize text that matches past entries. Its a huge time saver and has really made Safari usable for the first time in years.
It also feels quite fast, includes icloud syncing with tabs opened on your other IOS devices, and features built in sharing to twitter, iMessage, and Facebook (coming soon). The other nice feature of safari is the offline reading list, which gives you a text-only, book like approach to reading articles from various sites around the web. Simply send an article that you want to read later to your reader and enjoy it at a later time.
Great update overall and I highly recommend that all Chrome users give it a spin.