Battery life depends on your usage...

If i use WiFi and GPS...i can drain the battery pretty fast...1 day KO is pretty normal.

Bout the battery bar after dropping 1 bar, the subsequent bar will drop very fast is very normal. I do see this kind of situation in digital camera and my ipod as well. This is due to the fact that inaccuracy of the sensor ( forget the exact details ) .. Just like you using the speaker and blast at full volume while using GPS and Wifi .. you can see the battery bar straight drop 1 bar...but after awhile it will raise back.

If i dun use my phone extensively, it can last for 5-6 days like now during my exam season...no time play with it.