So I recently realized that the rules have been updated a bit in the third edition. I've had a look at the pdf over at Rio Grandes homepage, and this is what I found:
1) Completed cities consisting of only 2 tiles now score 4 points, instead of 2.
2) Farms now score 3 points for each adjacent city, instead of 4.
3) Farms also score differently now: Each farm area/field is scored separately from other farms.
Is that it, or did I miss something?
As a side note; I originaly misread the 1ed rules for scoring farms, and have actually been scoring them in the "new" way all the time. I was made aware of this quite some time ago and have been comtemplating switching over to the official version, but always decided not to because "my" version was so much easier to use. Guess that little problem just solved itself