download 'GPS status & Toolbox' from market. this works like a charm on my HTC desire and when GPS doesn't lock quickly. if this works on HTC phones with poor GPS signals, this should work on SGII as well.
I tried that when I was first testing the GPS, it never made a difference, but i'm getting some slightly better results now but still poor, I can lock upto 6/7 sats outside but they are not stable.
Still deciding whether to send for repair/replacement or not, I don't even use the GPS much but it's just annoying that it doesnt work properly.

Very weird, GPS seems to be working today, it took a few minutes but to my supprise it got a lock and stayed locked..

