Carrier :Celcom 3G prepaid
Is 3G working : yes
Is MMS working : yes
Is tethering working : haven't tried (not important to me)
Other Information/Remarks :

initially, MMS didn't work due to i missed out the last 4 digit number on the MMS proxy setting (:8080) - and works perfectly (sending and receiving) after inputting those 4 digits.

jailbreak using redsn0w failed few times, re-jailbreak successful after booting my laptop to "safe mode". (info gained from  Pwnagetool and Redsn0w , iPhone 3.0 Unlocking/Jailbreaking on the first page, tested by Shock).

no problem in downloading applications from both iTunes and Cydia, accessing youtube, no drop calls, consistent 3G signal while surfing - but sucks a lot of my airtime.

most noticeable change (cons) - sucks a lot of battery life.

for info, before restoring to 3.0, i was still using the old 2.2 firmware with 2.28.00 baseband, quickpwn+yellowsn0w unit from Australia.

so far very satisfied with my iphone, couldn't find any fault with it, period.

hope my info is useful to those who read it.