Jelly Bean 4.2.1 Upgrade... Silver lining after a Storm

If you have ever used an Android powered phone especially from v4.0 and above, then you'll agree with me that its pretty cool. I got a Samsung Galaxy Nexus for the sole purpose of getting Android updates first hand. I never liked the idea of waiting for ages for the phone manufacturer to make updates available.
My first software update was done immediately I powered the phone ON for the very first time, from 4.0 ICS to 4.1 Jelly Bean. It was smooth and the interface even smoother and I enjoyed every bit of the phone. Got a lot of cool apps and games to make the whole Android experience great.
My first encounter with the 4.2 Jellybean was on a Nexus 7 and it was really cool especially with the new features like multiple users, gesture typing and others. See link http://www.android.com/whatsnew/
So when I was alerted about a new software update from 4.1.2 to 4.2.1, I willingly accepted to update. THAT WAS MY BIGGEST ANDROID MISTAKE.
After the update completed, my phone got restarted and was all cranky like a patient just out of anesthesia, but I was not bothered, most software upgrades take a while to settle in so I waited but no improvement. I restarted the phone a couple of times but it was still slow. I thought I had seen the worse, but No, that was the curtain raiser. Before I could blink I noticed my phone indication low battery and it was very HOT. I mean hot enough to warm your bathing water at night. Ok lets charge it, seems the battery is overworking itself after the upgrade I thought to myself. It took ages to charge the phone from 0% to 50% and most times, the phone discharged in less than 4 hrs on standby and many times switched off without any notification.

At that point, I had had it, I really felt like throwing my phone out the window because it really SUCKED. Imagine a slow, hanging and unreliable smartphone? Terrible right? The only option was to rollback the software update but, I somehow stubbornly declined despite numerous involuntary shutdowns, crashing app and phone freeze
.I noticed that my email client was using most of my battery, much more than the display, so I started sending Bug reports for almost anything wrong on the phone. I  killed the process for the email client app and noticed the phone freeze were getting more irregular but the battery drain wasn't so  I made sure it was always connected to my laptop like a baby to its mother to avoid any unexpected shutdown.
I deleted the email account, deleted a few apps, restarted and some sanity came back to my phone. I later reconfigured the email client app and lo and behold, the fever was gone and the charging and battery life seem to be back to normal.

Not sure what the exact problem was but I think some software processes did not properly transit between the two software levels. though my phone is out of the ICU, its still under observation.

After all the drama, the 4.2.1 is COOOL but never worth the problems.