I installed Safari 5 on my computer last night. The vast majority of things work just fine.
I can’t really say I’ve noticed much of an improvement in performance but then I haven’t put the browser through its paces yet, either.
One major change is the introduction of the Reader feature, which allows you to read stories on news websites without the clutter of menus and such.
Just click on the “Reader” button at the end of the menu bar …

… and Safari will turn an article on a webpage from this …

… to this:

Just click on the “Reader” button again to turn the feature off.
Pretty neat trick, if I may say so — although I must admit advertisers and their representatives will probably have a different opinion on the matter.
One negative thing that did stick out, though, was behaviour reminiscent of Google’s Chrome when it first came out a few years ago.
The browser would intermittently be unable to resolve hosts and fail to display web pages.
It was eventually determined the trouble was its DNS prefetching feature, which you could turn off to solve the trouble.
Earlier today, Safari did something similar from time to time, too, although far less frequently than Chrome did.
And now that I am trying to replicate the failure, I can’t.
Oh well, I will share if it crops up again.
In any case, if anyone out there in cyberspace knows how to turn off DNS prefetching in Safari, lemme know. It might come in handy later!