Safari is a web browser made by Apple in an attempt to gain some popularity among Windows users. It was one of the fastest web browsers that you could find on Windows, but, unfortunately, Apple doesn't seem to care about the Windows version of Safari any more. Most of the features that are available in the Mac version haven't made an appearance in Windows.
Despite all this, I would still put Safari in my top 3 of the best browsers for Windows.
There have been some changes in Safari in its latest version, 5.1.7. The application now has a feature called Reading List. This allows you to save any webpage so that you can read it later, even when you don't have an active Internet connection. This feature is very useful for users who own iOS devices, like the iPhone or iPad, because the Reading List is synced across devices. For example, you can save a page in the Windows version of the application and then read it on your iPad. Another interesting feature is Reading View, which formats the text of a webpage, so that it is easier to read. It discards images, videos and other elements and presents the text to you with a darkened background that allows you to concentrate on reading.
In terms of speed, Safari is still one of the fastest browsers rendering pages and playing content. It is not the best, but it is very usable. There is no hardware acceleration available, which might mean that some websites that have heavy usage of multimedia might be slower than in Chrome or Firefox.
The bottom line is that Safari is a nice browser to have, especially if you have iOS devices. However, its lack of support make me want to favor Chrome or Firefox more. I would still take Safari over Internet Explorer any day, though.