Sounds low. Possibly bad battery in that phone, worth taking back to the store.

Battery life extension tips:

Change your email-checking frequency to its longest possible interval, which I think is 1 hour.

Turn off beeps/vibrations for the email feature so it's not constantly vibrating to let you know you've got an email.

Turn off bluetooth if you're not using it.

Turn off the thing that prompts you for new 802.11 networks, and don't join every network you see. Spend most of your time on 3G.

If you have low cellular signal strength where you spend most of your time, that could be the whole reason for the battery drain. Is that the case?