Here's the thing, most people don't hate her because of her tennis. She plays an amazing game, she works very hard, and it should be something admired. True, it annoys people how she literally just works on serves so she can ace her way through the match and, coming from a collegiate player, being aced all the time is the most aggravating thing ever. But it's only a positive for Serena.
However, it's her attitude that usually turns people away. First of all, she's a sore loser. Second of all, she treats everything she does wrong like it's just people picking on her. Thirdly, she's outrightly said she hates tennis. And lastly, she's been fined for threatening umpires and ball judges. She just doesn't seem like a nice person.
In my opinion, she also seems to play mind games on the court, which is a big no-no, and the way she slumps, physically and with her game is annoying. And YES the announcers do kiss her *** all the time. But hey, she #1 in the world for a reason.