When Canon upgraded the 400D to the 450D (larger screen and LiveView) they had to spec up the battery. This battery charges well, maintains charge for a decent enough time but having used this now for a good couple of months it is apparent that the Original Canon battery is in a different league to this battery.
I can shoot all day with the Canon battery, but this battery will only last a few hours at most. If you used your LiveView, Flash and regular reviewing of your shots then you can flatten this battery in no time.
From a price point - great.
As a Backup - great.
As a second battery - Avoid.
Spend the extra money and get another Canon Battery or another "equivilant".