I have never been to one of these events, so I can't report on sound quality, but the screen is immense, 103 feet wide. You'll be able to see the pores on the singers' faces, I'm sure.
It's best to get tickets in advance, though I believe they have not quite filled the ballpark on previous outings. Go here to sign up. You can order up to four tickets, and if the ticketing works as in prior years, you print them yourself.