Hip hop/rap is not my kind of music, but in terms of that genre, I think anyone who appreciates music/art in general can see that Jay Z does it extremely well.
I like a few of his songs and have worked security for a few of his shows. He puts a lot into his performances and is a nice, classy guy with a head on his shoulders. His business philosophy is not much different than U2's.
He was one of the few artists (U2 being in this group too) who actually acknowledged my coworkers and I and the job we were doing. Everyone he tours with, his management, staff, etc are first class people.
Jay Z has talent, you have to respect him for as long as he has been around and been successful, and he has grown up a lot from the drug dealing thug of the 1980s.
People need to chill out. He's opening a show. Be glad U2 has good relationships with so many diverse artists.
I don't go to see the opener. If the opener is good, then its a bonus. If not, I'll walk around, check out the venue, check out merchandise, get something to eat, etc. Its not that difficult.
I have seen Keane(Vertigo) and Snow Patrol(360) open and was very satisfied with both bands.