Compared to a high end, purpose built navigators there will be plenty of cons. Even more as new features for these high end devices are marketed as competition heats up...
For instance, try as I might I can not get "Mr. T" or other celebrity voices on the Navicore. So if these things are important to you, you will be disappointed. However, in using it daily since I got it I haven't been disappointed in it's intended purpose.

The beauty for me is that it gives me yet another reason to use my N800 instead of a laptop or my dreaded WinMo iPAQ.
It also solves the problem of "what's that" from passers by. They seem to more easily accept that it is a navigator and don't need explanations for why I carry it. They are also blown away when I fire up the Opera browser when a WiFi connection is present. I will check my email and then open a page to my local Doppler radar... I then usually hear... "mine can't do that".

As far as concurrent use goes I have only been able to replicate that one other time and it appears to be dependent on the start up order for the apps and their GPS services. I did notice that the GPS device was listed twice in the BT menu.

In any event, time to acquire is short so even swapping the BT device between apps is relatively painless.