Xobni will only let you store one phone number per person. But what if someone has a work number, home number and a cell phone, and you decide what to use based of his daily schedule and the time of the day?
It would be very convenient to be able to assign several number to a person, and then, when this person is displayed in the Xobni side bar, all his numbers would be displayed, and you could choose what to use.
Another problem with person contact is that when you edit it and add a number, you loose the information Xobni collected from e-mails, so if you added a picture for a person, or mistakenly set a phone number for him, you have no way to ask Xobni to use the person contact details it gathered from e-mails.
There should be an option to tell Xobni to revert back to use data from e-mails, and also there should be a way to edit this information or to add data like picture without affecting this information.