Bing (iTunes link, Free) is not just a simple search app, Microsoft has really taken interest in working on the user interface and features. The app supports speech recognition for search queries and an easy toggle to change search type from web to images or news and more. It also offers Bing daily image which works like the app background and also displays interesting trivia. You can view your search results via in-app browser. The settings area lets you select your Safe Search, Units and Screen Rotation preferences.
If you like using Bing or are just looking for good web search app then Microsoft’s Bing for iPhone is definitely worth a try!