I support competition with Google -- they pretty much own the Web search world, Yahoo, and Microsoft notwithstanding -- but I have to say, whoever designed the UI for Cuil did a pretty horrible job on the whole.
The front page is oppressively dark -- I understand that it's a "cool" color scheme, but it's psychologically stifling. The kludgy results page is even worse; it appears as though someone decided to use their 1337 Ajax skills to cruft up some new-fangled frames, which have been deprecated in design circles for years on account of they're also psychologically stifling -- they eat up browser real estate and you can't get rid of them. And of course the ill-conceived double-or-triple-column business. The frames would be bad enough, but now we're expected to scan the page in a nonintuitive way between them? Ridiculous.
And don't even get me started on the cheesy generic Web 2.0 gradients and that chromed-out out-of-place accordion menu. The content of the menu is interesting, but the positioning? The presentation? All pretty much awful.
Google may be tempted to bask in warmth of the flames directed at its would-be competitor. But it would be well-advised to consider Cuil's challenge seriously.
Cuil may not be in the same league as a search engine (yet). Its founders may have failed to appreciate simplicity, speed, performance, and search relevance to the extent Google has. But Cuil wins hands down when it comes to privacy: It retains no personal information at all.
Google talks a lot about the user experience, but it hasn't yet recognized that user control is the defining user experience.
Google could easily afford to let users choose not to their searches and IP addresses stored. Not everyone would care enough to opt-out and Google would still have access to enough user data to optimize its network and to target ads.
The fact that Cuil and Ixquick both work as search engines without any personal information proves search surveillance isn't necessary.
It's already possible to search Google without leaving tracks, through cookie destruction and the use of Web proxies. It's just not easy. If Google really wants to improve the search experience and to deprive competitors of a potent angle of attack, it has the power to make search privacy easy.