The built-in camera for the iPhone is a great tool, allowing millions of people to take high-quality photos and share them near instantly with friends and family when on the go. But the actual app used to take photos is fairly limited. Fortunately, there are dozens of tools on the App Store that provide additional options for things like focus lock, exposure control, and white balance, including Camera Plus.
This version of Camera Plus is the lite version of the app so some of its more robust features are still missing; but even as a free app, it provides more tools and features than the built-in camera app provided by Apple. With better exposure and focus management (major issues with the built-in camera) and instant links to your photo and video galleries (conveniently separated), you can interact with your snapshots much more easily. Flash controls, zooms, and time stamps are also nice additions and the whole thing works pretty quickly. That said, it doesn't provide enough additional tools to be a must have in this iteration.
There is nothing vital missing from Camera Plus, but at the same time there are no must-have extras in the free edition of the app. If you are eager to upgrade your camera, consider the basic features of Camera Plus as a trial run for the more robust Pro edition of the app. It's a powerful tool and a good upgrade over the bare-bones iOS app.