My daughter has wanted a camera since she was 2 years old. I bought her this camera (the pink flower edition) just before she turned 3. She loves it. The size is great for little hands. For the most part I don't need to adjust her fingers to keep them away from the lens.
She also has a Chicco Smile Camera. That was is very easy to use, and slightly cheaper since it uses regular 35mm film. However, given a choice she'll go for the Nexia every time. I know she's drawn to the design, but I think she likes the size of it too.
If you have your own little budding photographer let them give this camera a try. I don't think you'll go wrong.