I have a Galaxy W and they do have terrible battery lives! My battery seems to last about 12 hours...that's it!!
I have to charge mine every night, i'm up at 6am, leave the house at 7am to start work at 8am and I usually put it on charge again in the car for the hour drive to work, or I know the juice will probably run out before I finish work at 6pm!.
I then have to charge again it on the drive home, or it won't last the evening.
I hardly use my phone whilst i'm at work, except to check messages on my breaks, I shut down apps when not using them and don't let my facebook or email update automatically, but still the battery life leaves mush to be desired!.
I won't even get started here about the trouble i'm having with this phone on the THREE network *sighs* (oh, how i wish they would change their mind about releasing the gingerbread update for this phone, but they won't!)
I like the interface of this phone, but the rubbish battery life and the bugginess it has, particularly with text messaging, annoys the cr4p out of me!