His music is mediocre at best, he's done a few tracks that I thought were fairly good but on the whole he is just simply not that talented as a rapper. His music is either a straight up looping sample ripped off from somebody else, or predictable and generic, not necessarily bad, perfectly listenable but far from anything worthy of justifying either his level of fame or his opinion of himself.
He chose a wife that epitomises everything that is wrong with the culture of celebrity, she is basically famous for being famous and that being a thing makes me pity mankind, so by virtue of the fact he respects her he loses respect from me.
His levels of arrogance are frankly bizarre, claiming to be the Disney of this Generation? And meaning it sincerely rather than as an self deprecating nod to the fact they both ripped a shit load of stuff off of earlier artists with properly crediting them! Interrupting awards shows, self proclaiming his own genius, claiming to be the greatest performer of a generation... the list goes on and on. He is basically a twat, a self-righteous self-agrandising pompous twat, the Donald Trump of the pop charts if you will.
He named his kid after a fucking direction! Seriously, get a grip you colossal prick! Directions and names aren't interchangeable, that poor bastard is going to have to go through school, college (OK probably not college!) and then apply for jobs with a fucking compass point at the top of his resume.
His whole world, his professional life, his personal life, his social life, his personality, his demeanor, his attitude, just every single thing both about or related to him runs as a checklist of reasons not to like somebody.
TL:DR - He sucks. He really does.
Although having said all this there was an askreddit thread a while ago about people who worked in hotels/restaurants/etc that had met celebrities and what they were like, the few people who had dealings with Kanye said he was polite, down to earth, and a generally nice guy and everything I just listed as my opinion of him isn't really him but a stage persona, like his whole public life is one ongoing piece of performance art... Now to my mind this just makes him suck harder since rather than being afflicted with just being that way he has made a conscious decision to be like that! But for the sake of fair argument I felt obliged to point out apparently he does have a nice side when out of the limelight.