Dear Kian-Guan,
I used the G2 during a trip to Hokaido, Japan in winter 2 years ago. It worked just fine. There was a night I were shooting some ice shots and I felt if my fingers were going to fall down. The G2 seemed to tolerate the cold weather better than I^^.
After caming to New England I have used it in cold weather as well, and there was no problems at all.
Just remember to have some spare batteries.
Regards, Shu-Hsien