what new in ios 6.1.2? is it worth

The 6.1.2 update is specifically to address a bug with Microsoft Exchange servers. If you don't use an Exchange server for your email, calendaring or contacts, you don't need the 6.1.2 update.

Regards.

I just updated my iPhone 4 to 6.1.2 and now no-one can hear me when I make calls on normal mic or speakerphone.

No. It's weird... I can hear them, but they can't hear me. They're sying that can hear interference in the bg. I've tested the phone mic on video record and all sounds fine. It sounds terrible on 'Voice Memos' though with interference and ticking (which I'm guessing is what others are hearing on my calls). Was using it all day fine until I did the update.

Apple mentioned only the Exchange bug as being addressed.

Based on this thread "users r complaining abt mic issues in update" is not entirely accurate...

It would be more accurate to say "a user complained about a mic issue".

I recently updated to iOS 6.1.2 and have had no problems at all.

It's been a welcome improvement so far. I'm not able to sit and watch my battery drain from simply checking emails. It's only been a short amount of time, but if anyone was having ridiculous battery drain due to exchange, this update appears to address it.

yup, atleast bettry is not draining as fast as earlier.

Not worth the update numerous reports, including mine of various issues. I have 4s, after update the volume slider is gone, unless you plug in headphones. With out headphones you can not listen to music through speakers and will have no ability to adjust sound volume as the hardware buttons do not adjust volume either.

Really starting to get concerned for Apple. After maps fiasco then battery drain, now diabled volume... Windows phone or Android starting to look like a viable option. Sad... I love my iPhone and iPad but seriously concerned. This issue is QA 101 a middle school kid would find this bug...my 11 year old son did. 😟