Having had T-Mobile for the past 5 years, I recently switched to Sprint Sero and had one problem: CDMA - cmon.. its cdma! Battery lasts a day if that. Other than that, signal is excellent (Full signal everywhere I go I drive between Palm Desert, San Diego and LA on a weekly basis and used to drop signal on the 60. 3G is excellent i pull around 500 - 700k down using my phone as a modem. I would recommend the M1 as Sanyo has always been a steller phone for sprint (loudest speakerphone I have EVER used) Garmin Mobile works well when I'm not in my car (Honda Accord w/Navi) I use it while walking sometimes and even navigated my friend and I through Glendale last week with Garmin.. All in all I'm happy.