Did a fresh upgrade from 5.1 to 6.1.2 with JB.

Few things observe:

1. Charging reach 97% to 98% taking a while, meaning easily 15 to 20mins to increase 1%. Not sure - need to observe again.
2. Full charge to 100% at 10pm, play some games, 3G, emails for around 30 mins, battery still show 100%.
3. Left the phone with Edge mode until morning, 97%.

So far, the iOS respond is much faster than my old iOS.