Definitely a base for a really good tune. Ok, here goes...(I'll be nice

)
Bass: I would notch the mids, add bass and treble (the usual eq for slapping). Sounds thin the way it is.
Guitar: Come down in the mix a bit. Would also have him play longer sustained chords (add a bit of chorus) as opposed to the constant strumming.
Sax: Come up in the mix a bit
Drums: Play a more steady groove. Since the bassline is a bit busy, it doesn't sound good when both of y'all are playing busy. Makes the song really 'loose' sounding.
That's just how "I" would arrange it. But it's not my tune!
Overall, I like the tune.