SearchIt is dead simple, and that's the way its developers intended it to be. In some ways, it replicates pre-existing iPhone functionality: it searches the web, the news, images, and Wikipedia, and that's it. But what makes it worth looking at is its speed and simplicity—sometimes, you really do need something faster than Mobile Safari, and SearchIt is just the app for the job. Unfortunately, SearchIt isn't perfect, and Safari is good enough that many don't need a dedicated search app, but SearchIt is useful on occasion. Better yet: it's free!
Open the app, and there's a shiny red search box waiting to be used. After entering your query, you can select from the Web, News, Wikipedia, and Images tabs. Information is displayed in a more iPhone-friendly format than on other mobile sites, but other than that, nothing is noticeably different other than speed.
The speed is what makes SearchIt worthwhile, though; take it from a girl who's using barely-working WiFi at school. Where Google sometimes timed out, SearchIt worked. Nice! Even with a solid connection, SearchIt loads results noticeably faster.
The app isn't perfect, even if it is speedy. Images are only displayed eight thumbnails at a time, and there's no way to adjust the default (though you can always tap "display more"). I also encountered a few Wikipedia pages that, for some reason or other, refused to load. The in-app browser doesn't always render properly, and it's easy to get pushed back to the search results if you accidentally tap a button. However, there's an "Open in Safari" option that should do the trick as soon as you find what you're looking for.
There's not much more to say about SearchIt. It serves a niche of people who want a no-frills approach to search, and who want quick results. If that's what you need—congratulations, SearchIt is free and it should suit your needs. If not, then that's fine, too, but you'd be surprised at how often a simple search doesn't require Safari. There's a reason people download Google's search app, and personally, I think that SearchIt beats that one by a mile.