I first used it with OS .75 and it was terrible. The standard battery was better. Went to OS.99 and beyond and its fine-better-2-3 hrs more I think. I like it.
If you go with the Extended Battery 1600mAh OEM Size for BlackBerry Storm make shore you charge for 8 hours and be for you charge it again make shore it is all most dead and it will take 5 to 7 charges be for you will see it lasting longer