I love the groove man! The vocal chops should have a bit more reverb and should be a tad more quiet. The arrangement makes it very pleasant to listen to! As for the mastering, you should consider improving your mixing before focusing on the master. Yes, you can hide flaws of mixing with great mastering, but to some extent. I personally like well mixed tracks with any level of mastering over not so well mixed ones with "super good" mastering.