Overall, this is a good demo reel. However, you may want to liven up the first couple of scenes in your reel. Your artwork is very good, but I've literally seen people stop reels halfway and ignore the rest because they weren't interesting. Try keeping the reel watcher getting more and more. And don't save the best exactly last.

Try to put some of your best first to keep the reel watcher's interest. It would suck if they never saw your best because the movie was too long or somethin. Also, they may not like Superman, so try choosing a song anyone would like. (Found that out the hard way....).

Go to https://pixar.com for a good faq on how to do a good demo reel.