NOTHING!
This is a great phone. It has withstood all kinds of abuse, including almost a daily drop onto a concrete floor (one drop killed my Samsung).
It will pick up a signal where other phones won't. It sounds good when other phones don't. The slider design is the way all phones should be made.
I just wish I could see the itty bitty writing on the screen. You can even see the display in the sun, and it's great that the time displays all the time -- you can glance at it without having to do a thing (and it's big enough to read).
Great phone. I retired it because I wanted a phone with a camera. Not sure that was a good reason to give up this perfect little phone.
I had a Kyocera flip phone. It is an invincible phone. I dropped it on the concrete several times in a row and it stilled worked. I got so confident I even demonstrated how durable it was by purposely dropping it on the floor and it didn't flinch. But I had to move on to a camera phone and slider phone, which I wanted for a while.
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