I have the Samsung ATIV SE switching from an LG Android to Windows. Really like this Windows Phone. I can pin often used numbers to the Desktop and have on the Main Screen all applications that I often use.
The problem I have with the Samsung Phone is not Windows it's the hardware. The Volume Button on the left of the cell phone is in the wrong position. When picking up the phone I often accidently lower the volume without realizing this. I receive calls but do not hear them because the volume is off or too low. This is my main complaint about the hardware. Another item I'd like to see changed is the Power/Lock button which is to the right of the phone across from the Volume Button which is held too while picking up phone. My previous LG phone had this button on the top which was nice but I can live with this button on the right. Phone does not shut off that easily.