I'm planning to buy the Galaxy S2 because i'm a fan boy of android. But now with 3G connection how much can the battery stands for ?

Please can you share your experience with this mobile with 3G and battery life ?
Mine lasts a day on moderate use. You would definitely have to charge it every night.
It is not a problem to charge it every night with moderate usage with 3G on all the time. Can you please share the "Battery Usage" info ?
1d 2h 8 min 40 sec and still half of the battery, didn't use it much other than whatsapp and angry birds. But on a worst case scenario it will last 1 day. Of course this includes working continuously on the phone for more than 2 hours.

The two biggest power consumers are the OS and display. Always.
Ahmad_k wroteIt is not a problem to charge it every night with moderate usage with 3G on all the time. Can you please share the "Battery Usage" info ?
As noted above, Android OS is the bulk of the usage followed always by display. If you set your display to automatic, I usually find that it doesnt consume an enormous amount. Since you say you dont mind charging every night, I dont think you will find battery life a problem.
it depends what version of android you are running. there is a know android os bug that drains the battery that was fixed in 2.3.5 so make sure you run the latest. most custom roms have it fixed as well as the kernels. best for me was 23hours with 4 hours and 30 mins on screen time which is great.
My Galaxy Ace used to go up to 3 days on a single charge but without WiFi ,GPS enabled and my brightness was low.
Since the SII has a bigger screen I would say a maximum of 2 or 2.5 days.