Nope don't think it would do better.
Like most said, on PS3, its REALLY REALLY Killzone 3 thats affected the sales.
I mean its not even funny, its that obvious.
On Xbox 360...300K Week 1 for a Epic Game is under-whelming, and the GEOW3 beta helped it a lot too.
Maybe Bulletstorm simply didn't resonate with audiences, maybe the marketing didn't convince people to give it a try, maybe FPS' are being oversaturated (as Killzone 3 itself has declined from Killzone 2 in sales week 1). Who knows, we;ll probably never know.
All hail the KING, Andrespetmonkey