Always looking to the future we've decided to give Safari 4 a whirl to see what's around the corner.
The first thing that sticks out is the new 'Top Sites'. This is very much an overview page showing your most browsed sites. That might not be a good thing for some - but for us, we liked it.
This can be edited by clicking the 'edit' button at the bottom of the window.
This in turn reveals some controls for manipulating the results.
Personally I would like to see the ability to explicitly decide which pages I want (not necessarily my 'top sites').
Looking through your bookmarks now gives you to use the ability to search in cover-flow mode. It's useful for certain situations and annoying for others. It takes a little time to update all the thumbnails.
Search is improved and seems rapid from testing so far:
From early testing browser rendering actually seems very similar, more time will be required to determine if we see noticeable speed increases.
Verdict: Thumbs up!