I was not expecting this unit to hold the charge for long, but it does.  I have had it now since Sep 2011, it is still going strong.  Holds the charge for weeks.  The only item that I use it to charge is my phone.  I am happy with this purchase.  I have not tried to use it with any other device, but it delivers with my phone, more than I had hoped for.  The device itself is made of plastic, sturdy and reliable.  The power button is still going strong.  It has not worn out, the led lights showing the charge remaining still work.  Although, it would have been nice to have an lcd showing percentage from 0-100%.  I don't have anything to add for improvements, other than the lcd.