Hi I m using sony xperia m here is my experience with this phone .
first of all its major drawback is all apps are stored in device memory not on memory card so u can not save more apps.
second when gprs and both sim are active or even wifi is active it start restarting again and again so to keep mobie phone functioning properly we have to use only one sim and other sim remains deactive. I talk to customer care once they ask me that this is software problem then I reinstall the software but problem remains same. I show it on local service centre they also ask that this is software problem then I ask them that I have reinstall it they ask then there is no solution for it.