Ack! Such ignorant speech!
Peach is a terrific character. Her floating abilities allow her to dodge things much more easily than other people. She has everything I could want in a player: stellar recovery (making it virtually impossible to SD if you have any skill), a counterattack move (

which works great against anybody more powerful than her, the most demoralizing throws (okay so maybe that's not a big deal), a projectile attack, a side + B that will hit through anything, a move that will get you items when they're turned off, the list goes on. (ever pulled a bomb or home-run bat out when items are off? ... "Where the heck did that come from?"

)
And if you don't like her final smash then don't play her. I think it's awesome. Peach is really good for hovering out way off the edge of the stage and attacking players still recovering. Her final smash allows you to do that easily.
Plus, Peach's smash is the only smash (that I'm aware of) that actually benefits HERSELF. Peach is the only character I can consistently win a five-life game without losing a life, simply because she can recover health easily. Her smash allows her to get easy KOs on those who it would be otherwise difficult to KO.
If I had to criticize Peach, it would be for her lack of strong KO moves. She can deal out damage better than most, but it's hard for her to KO somebody. Usually I end up hitting them a little bit off the edge, then aggressively beating them back farther and farther until they can't recover anymore.
But seriously, she's an awesome character. What could be better than taunting "La La La LaLa La" when you ko someone else?