The new firmware has released for few weeks already and I was qualm to update it since I heard a lot bugs been given by this V12.0.013. The update is limited to few countries as the Nokia N series phone required to initialize the country product code before the update.
My attempt to update the firmware was futile due to my country product code were not on the update list. Thus I downloaded NSS Nemesis Service Suite for product code amendment.

Can’t be update due to no availability product code in list.

Altering the phone product code.
1. Click scan button to scan the phone. Phone need to be in PC suite mode.
2. Click read button to retrieve the info of your phone.
3. Change the product code that enable for update. I used the APAC since I’m in Asia Pacific Region. For the code you can refer to here http://allaboutsymbian.com/forum/showthread.php?t=58225
4. Check the box to enable the alter modified
5. Click write to have the changes applied.

Now open your Nokia Software Updater and start update.

Amended product code and ready for update.

It takes approx. 30-45minutes depend on the internet connection speeds and it will restart the phone few times.

The Result

Enchancement of GPS wit A-GPS where it able to lock satellites is shorter time and able to lock indoor as well wit minor data transfer that involved 3G/GPRS.

The 3.5G enabled.

This is wat I can feel wit the new firmware.

- Wifi connection become stable as it doesn't disconnect much and much faster.

- Viewing gallery speeded up.

- Switching to camera mode speed also increased.

- Battery last longer (source from lowyat.net coz I'm not sure as I haven't test yet)