It's nothing special but it'll smash just because it's Katy.
And maybe it's just me but it sounds A LOT like a song Fun would sing.
I agree with this.
She probably chose a weaker song as a lead single purposely, because she knew it would be a hit off her name alone and wouldn't have longevity anyway. This way she saves the best for later, giving the album the much needed longevity.
The chorus is infectious, the verses just barely good enough. The chant is repetitive, but that's beside the point, it's a damn pop song.
This is the type of song that you can listen to non-stop for about 2 weeks, until the novelty aspect wears down and you're left with yet again, a shallow Perry pop song that offers nothing new and nothing substantive to the genre.
And, I can't help shake the feeling that this is geared toward a younger crowd. The image of a 13 year old girl whispering "you're gonna hear me roar" as a tear slips onto her Girl Tech diary cannot escape me.
I use 
