yeah, this would definitely benefit from live piano and sax. those samples are probably the biggest issue with the song as is, and some live performances could really help bring it all together. the flute sample at the end was probably the worst of the three, but it's not exposed for as long.. i'd at least try to find a better sample for that one. i also thought some of the drum rhythms were just a bit random at times, particularly some open-hat/ride patterns around the middle portion of the song. nothing too severe though.
just doing a quick source comparison, as has been said before, it seems a bit like a conservative/somewhat stripped-down version of the source, but the genre conversion is successful, perhaps just a bit more original writing and embellishments would give it a little more character.
anyway, aside from those samples, this is pretty good. i highly encourage you to find some live performers (shouldn't be hard, everyone around here is a piano or sax player ), or at the very least try to get some better samples in there. nice work, and best of luck.