You can't easily change lenses with your smartphone's camera, so you have to change apps if you want a different shot. Camera ICS adds a much-needed zoom lens to your smartphone, but adds a bunch of other unwanted stuff too. The zoom isn't worth the jittery performance and ads that come with the app.
The app's misleading name makes you think it's a big update to the camera in Ice Cream Sandwich. However, it works with older versions of Android and doesn't even look like the Ice Cream Sandwich camera app. Instead, it's a modern-looking camera that sacrifices tons of screen space for ads and menu buttons. It does add a cool digital zoom, but it makes the camera's shutter skip and jump all over the place. Taking video with Camera ICS is technically possible, but really difficult thanks to the awful performance. You probably won't see this as much of an upgrade over Android's default camera. That's unfortunate, because there is room for improvement with the built-in camera app.
Though this app does add more features, it sacrifices all of the smooth, fluid performance that Android's camera has. If you're looking for a real upgrade to Ice Cream Sandwich's camera, look elsewhere. Camera ICS doesn't deliver on it.