From Atlantic Refugees:
le nubian: don't think you give Nolan enough credit - or his brother. I read the short story that predated "Memento." I've seen the movie backwards and forwards (special edition DVD). I have to say the movie hangs together both ways. In reverse order - the way Nolan intended it - the viewer feels a bit unsettled like the protagonist.
I read the short story too, and saw it played forward--thought it played better backwards, as Nolan intended.
Stuff that had me scratching my head included killing someone on the basis of a tattoo on your body that you have no memory of making (what if someone had done it to you, or you had done it on a drunken spree?) or a note scribbled on a photo; how unlikely it would be for a cop to develop a mentally handicapped man as a serial killer; and why the hotel clerk would let all the shenanigans go on for such a long time (I'd buy it if the clerk was in cahoots or intimidated by Pantoliano, but Nolan didn't go that way...).
Stuff like that. Hitchcock's films had loopholes too, but he made you forget the loopholes, mainly because he was freaking you out with the same fears and anxieties that freaked him out too...