How long should my iPod Touch Gen. 4 battery last?

I charged it 2 1/2 ago (fully) and was on Facebook, Talking Ben, Doodle Jump, Skateboarding Rat and Finger Slayer since then for about 2 hours max. Please tell me how long yours (about) lasts? Only if you own/have used for a period of time, an iPod Gen. 4 please. Not Gen. 3 or anything. Thanks! Oh and it's less than 6 months old.