There are lots of problems with OmniWeb, but I have still bought a Licence, and don't regret it one bit.
Tech support and bug reports and replied to within the day usually, and it is far and away the best looking browser, and just does everything the way a browser should (UI wise I mean)
I keep Chimera, IE, and Omniweb in my dock, and switch between them. Chimera is best for sites with large pages (like these forums), IE for compatibility, and Omniweb for just plain pleasure of use.
I can't wait for OW5.. OmniGroup are writing their own lightweight objects for rendering the page, which should improve performance no-end, along with promised full support for CSS and Javascript, it will be a killer browser.
The big reason I like OW? try using the 'RESIZE' widget on any other browser, only OW knows how big the page is and resizes the window by the correct amount, all the others just go full screen (STUUUUPID!)