I'm a pretty major hip-hop head so i hope i can be of service.
I heard that instrumental before, it's by a youtube producer called TinoxBeats. I like it, a lot of emotion and energy in it.
The same can't be said of your friends rapping. No offense but i gotta say that this was pretty shite.
His lyricism is okay, he knows how to rhyme words. The rhyme patterns are pretty standard but he changes them a few times throughout the song, which is good to increase the variation. That was the nice part, but he lacks in three vital areas.
Delivery - This is the big one, seldom have i heard someone so disinterested in what they themselves are saying. Its a droning, monotonus blur of words that catches no interest from the listener. Also, he has to match his rapping to the right beat. I put the instrumental below, does that sound laid back to you? No it sounds really emotional, if you're gonna rap over that you'll have to be extremely passionate and intense or it will sound mismatched. You also have to think of the pitch, he was far below the instrumental. It didn't fit at alll.
Flow - It's sluggish and remains constant throughout the whole song. Generally that is not a good combination. Some rappers can pull off a sluggish flow by being really melodic and soulful. Consistency can be good if you are delivering a cohesive narratice.In this song the flow makes a boring delivery even more bland.
Content - He's trying to say something worthwhile, which is commendable. But he just doesnt manage to pull it off. He rabbles a lot of semi-philosophical statements but the message is unclear and the points doesn't go anywhere. Its also impossible to make an emotional connection due to the delivery and the metaphors are half-baked and doesn't really make sense.
To finally top it off, the chorus was impossible to tell apart from the normal rapping.
Rapping is hard, it takes years of practice to get even semi-good at it. I don't know how long he's been doing this, but if he wants to seriously pursue it he should invest in the book "How To Rap - The Art and Science of The Hip-Hop MC". It adresses pretty much everything you need to know about rapping.
Also, he should listen to a fuckton of rap. That way he will subconciously pick up how it should be done. He in particular should listen to some of the more animated rappers with strong flows and delivery. Tech N9ne, Ludacris and (i'm serious) Nicki Minaj all fall into this category.