I could definitely tell what Tarantino was trying to achieve here, originally. The movie's tagline describes this: "Six players on the trail of a half million in cash. There's only one question... who's playing who?". This was meant to be the (rather awesome) type of movie where an elaborate scheme is slowly given away, showing you which actor was where and doing what during a certain timeframe, leading to an eventual twist or realization that leaves a smile on your face for a while after the movie has finished. That would've been awesome.
Instead, you get an extremely predictable film with dull dialogue, a dull main character, dull events and writing that isn't even that good. From Tarantino, no less, which makes it all the more tragic. The movie is way too long and has no real twists (my first assumptions were always right, whereas a properly done version would have been the opposite).
Now, that could be, for some odd reason, on purpose; maybe the idea was to make a dull parody of an exciting type of movie... but somehow, that strikes me as a bit pointless. Dull has never really been a word I'd have used to describe Tarantino...
In a sentence:
A good premise, but poor execution. This leads to the whole film feeling dull and predictable, which isn't improved by the main character's terrible performance, but is slightly dampened by Samuel L. Jackson's awesomeness.