Honestly E-40 problem isn't his rapping, its his beat selection. There is no reason to have 8 or more consecutive albums that sound exactly the same.
I can't speak on his beats really but his rapping is ultimately what made me lose interest. At first his style and slang was just something he did and was really unique. Then when people were like "wow that's cool" he seemed to push them as his thing which makes sense, and seriously, in my opinion at least, which seems to be the unpopular going by his track record, ran them both into the ground. I mean on the first couple The Click and solo albums his style sounded natural, it was just how he sounded. After that as he got more popular it became kinda of his niche and he really started emphasizing it and it sounded force and unnatural which really made it weak to me personally. I've said this before, whatever. Just my opinion.
In a Major Way is the last album I liked by 40.