I think there's more interesting here than just the
difficulty of creating this work in MSPaint, although the difficulty was clearly very high. The guy says he did it this way because he didn't know any graphic software.
I think it would have taken less than 500 hours to learn how to use graphic software. But hey, that's just me. :-)
BTW, reminds me of this one:
http://cellar.org/showthread.php?t=1176