I own this and it's great. But that's hardly what we're talking about here when it comes to comics, it's basically a book that happened to work best as a graphic novel and I'd say it's closer to the exception than the rule. It's hardly Wolverine or any of that other superhero nonsense.
Also, please list some of the other "countless" examples, if they're anywhere near as good as Maus I will check them out.
Waltz with Bashir
American Splendor
Pyonyang, Shenzen, Jerusalem and Burma Chronicles by Guy Delisle
Perseopolis
Contract with God by Will Eisner
Anya's Ghost
Encyclopedia of Early Earth
The Incal
Metabarons
Road to Perdition
List goes on for a while really. Worth checking out. Probably won't like all of them but they're all certainly worth a look