My kit arrived today. I also am a Linux user, so I can post some impressions when I'll find the time to update my tablet to the 2.2006 OS (it's required by specs, I think for bluetooth improvements) and to install the Navicore kit.
BTW I already am a Nokia GPS owner that works very well with MaemoMapper (thx gnuite for it, I already contributed via paypal!) and it is the main reason for which I decided to try the navigation pack (one of my friend needed a GPS,too)
There is a new review of the kit on http://planet.maemo.org