Downside: The search engine cuil.com (pronounced cool) doesn't give you as many results as Google. (Case in point, I was looking for a recipe and found it via Google but it didn't show up in cuil.)
Upside: You get more info about the link and the info in context. And it's delivered in a more readable format. I'm able to make a better decision on what is really what I'm looking for. You can also add a cuil option in your Firefox search bar.