Bought this for the calendar function as a gift for someone who has difficulty remembering what day of the week it is. However every night when it goes into sleep mode, it "forgets" what mode it is in and it has to be reset every morning (three presses on the mode button on the back) which is beyond the ability of the person who I gave it to. This defeats the object of the purchase.
The lack of backup memory means that it has to be completely reset (day/date, time, sleep hours, etc.) after a power cut. When doing this it occasionally cuts out and you have to start all over again.