Our favorite thing about this picture is that Mario can see the scoreboard floating in the sky on the left. Also, he seems to have a nice view of the sun setting while he's running around saving princesses.
If you like this picture and want to see some more first-person Mario, you might also want to check out Techeblog's Doom/Mario mash-up. The poor goombas -- they never stood a chance, really.
[Update: The picture now links to a wallpaper sized version -- just click on it. Thanks, Jeff!]