[Tooluka]

My 3GS works identically on v5 and v6. No performance or battery life degradation, no new lags. My friends with 4 and 4S tell that battery life actually improved, especially for 4S. Neither of us use jailbreaks of any kind.

PS: and as for iPad 2 I'm not sure about battery life, I rarely discharge it from 100 to 0 in one session.