I took my phone off charge yesterday morning at 8am. By lunchtime it was 54%, thats with wifi on, gps on and some Market browsing and around 10 texts. By 10pm the battery was on 38%, again with gps, wifi on, some market browsing, around 10 texts and prob about 15 mins calls. Left on over night (not charging), at 8am next day, battery was 34%. I've had it on all day, more market browsing, playing around 20-30 mins games, few texts and around 15 mins calls and at 15:20, the battery was at 5% and I put it on charge.
The battery life seems to drop rapidly then settle
My phone is only 2 days old and I have my screen brightness set to 50%.