Most CGI cartoons look fantastic, whether on Blu-ray or standard DVD. A reference title should really be a standard live action film that shows the full benefits of BD, although I'm yet to be fully convinced of much superiority of BD over DVD, especially as they initially cost nearly double. I have a few BD's, where the picture is better than the DVD version, e.g "The Thing" and "North by Northwest", but then the companies that released them have not brought out an up to date DVD version that can be compared with them. Apart from sprucing up the PQ and SQ, the only difference I see with BD's is that you can go right up to the screen, and the PQ is still crystal-clear, unlike a DVD, where the picture is blurred/pixellated, but at normal viewing distance, the PQ is no different. Also, many BD's are actually worse or no better than their DVD counterparts.
For PQ and SQ reviews of all past and present BD's, check out blueray.highdefdigest.com or uk.bluray.com