I felt the same way for a long time, even after several attempts at figuring out why everybody else seemed to love it. Then I was linked to one particular strip*, laughed my head off, went through the archives, and fell in love. You definitely need that click moment, but once you're in it's pretty much self-sustaining. Overall it's about the flow of dialogue, the character's voices and interactions, and a unique brand of pathos that gives it a bizarre and nigh-unexplainable sense of reality.
I wish I could give it some concrete props instead of this ethereal crap, but in the end you get it or you don't, and if you don't then you shouldn't worry about it, it's not on account of a flaw on your part.
It's a weird comic.*: For the record, it was
this one, though you probably shouldn't expect it to do it for you. Frame of mind, etc. etc.