The fact is this: I find it incredibly daunting to try and say something about Maus which has not yet been said -- or, rather, it's not that I think I could come up with something that hasn't been said, it's that I'm scrambling to find something to say that doesn't somehow reduce it or try to set it in to some box that attempts to contain it.  Maus is the worst nightmare one could ever conceive of having... made all the worse by the fact that it's true.  It's real.  This happened.  Granted, not with mice, but with human beings and even by distancing ourselves by anthropomorphic characters, the horror and agony and despair is all still there.  Art Spiegelman captured it in such deceptively simple artwork but somehow still acknowledges that this is only one part of a much larger whole.

I won't try to dissect it or even really try for intelligence here, but these slim graphic novels are a very vivid reminder of the worst of humankind's history (and yes, it's certainly worth noting that it is chronicled using animals to represent people).  I was prepared for that part of it, I suppose, (well, as prepared as anyone can be, knowing they will be reduced to tears over a Holocaust story) but the things that hit me hardest of all were the moments that remind you that this story is being told from the perspective of a human being with flaws and problems. The father-son storyline was heartbreaking and when you can say that in the midst of a story that breaks your heart in every single frame, then that's something.
If you haven't read either volume, I encourage you to do so. 

Frequently, I feel like I've been hearing people say that we over-emphasize the Holocaust when there are so many other atrocities and while that's true -- there are many other incidents that deserve our attention - -I'm not sure you can ever emphasize something like this enough until we are no longer at risk of having such a thing occur again... and even then, one should never forget what we are capable of doing to our fellow beings.