Awful. Truly terrible, I can't believe anyone could call this music. They don't even seem to follow any rhythm or melody with their lyrics.
I guess this is what they mean when you start feeling old. I can't connect to this "music" in any way. Does it even have notes.
This is a new-ish sound which started from British/UK rap(and UK grime). Here's an example:
East coast US rappers adopted it and made their own slight variations which spread to other states. Here is an example of Drake trying the flow/style:
It might not sound like it at first listen, but this is much, much better than the mumble rap of the 2010s, which has been mostly left behind(and thank goodness for that). I just consider it to be faster-paced rap/hip-hop and it has slowly been morphing into a sort of house/techno/rap mix lately:
(I could picture this song in a racing video game like Midnight Club of NFS Underground).
On a side note: It's a shame that Eminem didn't try this style. Here's an example of how he would have sounded with it.