I'm on 5.1 jailbroken, so my question is, is it really necessary to update to 5.1.1 and jailbreak again?
I honestly don't think it's worth it since I'm happy to be on 5.0.1 as of now. So if you're happy with your device now and are lazy like me and don't want to update and re-jailbreak, I'd stick with 5.1. Or if you simply can't live with an update being out and you not having it, do it.
My iPhone 4S is still on 5.0.1 untethered jailbreak and I'm happy with it. I don't really see a reason to update since you can get tweaks to replace the features the update brings. It's also a pain in the butt to update and backup all your cydia apps and stuff and then jailbreaking again. I honestly don't think it's worth it since I'm happy to be on 5.0.1 as of now. So if you're happy with your device now and are lazy like me and don't want to update and re-jailbreak, I'd stick with 5.1. Or if you simply can't live with an update being out and you not having it, do it.
personally, i gained on an average about 1-1.5 hours usage of battery life per day
that alone IS worth it to me. of course, ymmv