Hey guys i bought iphone 3g last week and it is not unlocked anyway am gonna unlock it by usind with EXtra SIM ..

My question is i hear that T-mobile have 3G network so is it gonna be ok to use that t-mob 3g with my new iphone 3g' i mean the internet the gps and all the rest?? i heard it is not gonna work with the Gps but am ok with that if the internet is fine ?? any answer guys this is my first time here ... thanks