Display very difficult to read for me - no matter how you set contrast, extremely slow in updating data, cannot search for a string (unless it starts with the very first word of an entry). When saving data as csv on a PC, it tends to corrupt it and does not reload the info back correctly. It cannot duplicate entries for other dates. I could not get it to synchronise with Outlook. It is all too easy to delete all items in a category. The schedule summary mode shows only times, not dates!
The telephone directory by default shows only unsorted and when you get to the appropriate directory, it shows fairly useless shortened forms of the info. You have to set it to 'search' to reveal any useful data. Therefore I do not recommend Sharp ZQ-590.