I have had trouble with the GPS on the Xperia Arc. You can see a track I recorded at http://g.co/maps/h8dw compared to a track recorded simultaneously on a Google Nexus One handset. The Xperia Arc track is of poor accuracy. Further investigation with the application GPS Test showed much lower numbers of satellites observed and higher signal to noise ration on the Xperia Arc satellites, suggesting an GPS antenna problems. Holding the the phone face up at arms length did not improve the GPS performance of the Arc relative to the Nexus One. Oddly, I can't find reference to discussion of Xperia Arc GPS accuracy problems in this forum or elsewhere. The GPS gets a fix quickly and is good enough for figuring out approximate location and getting directions with Maps but is awful for tracking.