It has been just over a month since I purchased the SPH-a680 and the phone continues to satisfy my requirements. I'm a light user, but I do carry the phone with me to work and any other time I am out of the house. Battery life (I use the Power Save mode that dims the display) and signal strength have been excellent. The phone is charged about every 4 to 5 days. Voice clarity is good. There is a minor issue when calling another person who is using a cell or cordless phone in that sometimes it sounds like the phone is cutting out. It's just something that you need to get used to. I have not tried calling from a corded phone to see if there is a difference.
I really wish this phone had a speakerphone. As I mentioned in my initial post, you can voice-dial names or phone numbers. A speakerphone would have been very useful with this feature.
When you bring up the phonebook you are given a choice to search by name, entry or group. Each entry is identified by a three-digit number, an icon and then the name. The three-digit number and icon take up 1/3 of each line, which means if your name or phone number is too long, they both scroll, which is annoying. I'm not sure why the three-digit number has to be displayed. Also there is no way to change what format (name, entry or group) is first displayed.
One major annoyance is the lack of a mute or privacy button, that turns the ringer off and turns on vibrate mode. Instead, you have to flip open and using the side scroll button, scroll down until the ringer volume is in vibrate mode. On my old phone you could press and hold the # key to activate vibrate mode. Much more useful.
It is easy to the use the phone with one hand. The keypad is not flimsy and provides good feedback whenever a key is pressed.
Overall, I would recommend this phone.