It took a little bit more than a few weekends, but after a little bit of adding details it seems to work for now.
Pictures can be seen in the linked flickr album.
It currently can mesure temeprature, pressure, humidity, rain and wind direction, wind speed gets added later.
That wiring certainly doesn't look like the easy way of doing it!
It is easier than many other ways and it mostly reduces mistakes as its mostly point to point wiring, but for more than prototypes it is not suited.