Like these guy's said, you've got a good voice for rapping. There was a couple of bits where it sounded like your vocals slid if you know what i mean, which i didn't like. And at some bits it sounded like you had some spit in your mouth so your voice sounded muffled. I like the ad libbing but you should stack and pan them to make them thicker. I couldn't really understand the hook, it sounded pitched down a little bit too much to me. I also thought the song sounded sparse too. That's probably down to the beat and the mixing but you should double your vocals or put some backing vocals behind your main ones. And for some reason it sounded like you did all of the verses in one take. You should probably do 4 or 8 bars at a time to keep your mouth clear.
Overall 7/10 for the vocals but 5.5 or 6/10 as a complete song. It sounds mostly empty to me. The rapping is good though. With some work it could be pretty good but right now it sounds like a cheaply made mixtape song.