Love the app so far.
There are some logic functions missing though. First of all, if you're using any kind of messaging technology (sms, mms, im, mail), you need to have some kind of visual notification. Just audio just doesn't do it. I mean, on the n97 you already have the online/offline icon inside the contact widget.
Second, the Ovi Chat contacts has to be manually linked to your phone's contacts.
Of course it's still in beta so bugs and options will be fixed and added. Can't wait! :-)
PS: Add online/offline status to phones contact on the 5800 and your golden ;-)