The Instagram camera is good because the app improves the camera function by some technique to boost the picture quality. However, Instagram camera performance is mostly as a result of the device. For instance, if a person is using a phone with poor camera quality, the Instagram of that camera will be based on the lens of the camera of the device, if the lens of the devices is dull the picture will come out bad, but with the enhancer of the Instagram camera the picture will look a little bit better.
However, if a person is using a device that has a good camera such as iOS devices, which are known for their quality camera, a picture taken on Instagram with this phone will be very nice, because of the camera lens and the effect of the Instagram filters on the picture. In summary, the Instagram camera is based on the lens of the device used to take the pictures.