[Update: My problem turned out to be the compass being install on the wrong leg and NOT the update . Probably still good advice to think twice if you like how your Phantom flies, but I no longer have any significant issues with 3.10. ] Since there seems to be a lot of encouragement to move to the new firmware, I wanted to start this thread to ensure anyone thinking of updating thinks twice. My Phantom was great prior to the update. Amazing really. Would just sit in the air, lean into the wind, and stay. I could let go of the controls for minutes and it wouldn't budge (I did this once when my wife came out to ask a questions and it just hovered where I left it the whole time). HOWEVER, I made the mistake of updating to the new rev. Now GPS mode is unusable. ATTI is still great - smooth, doesn't drift unless there is wind. As soon as I flip to GPS, though, it picks a random direction and flies off (I can override with the stick, but it is a constant battle). I still hope to find some configuration that will fix it but if you like the way your Phantom flies my recommendation is to leave well enough alone.