Der Spiegel has a nice article about the negotiations on Kosovo's future by the trio Ischinger, Wisner and Bozan-Kharchenko. The long article gives a good description of the people involved and tells a bit about how the negotiations went.
In my opinion the biggest failure of the negotiations remains the onesidedness. When it comes to principles the principle that Belgrade won't rule Kosovo anymore is on top. But the principle that the way in which Kosovo is treating its Serbs is unacceptable and that they need just as hard guarantees keeps missing.
These two principles are to a certain extent contradictory. But I believe that as long we we don't recognize this contradiction the conflict is inresolvable. The claim that the Ahtisaari proposal is enough for Serb minority rights is in my opinion just ridiculous.
The article tries to put the blame for the failed negotiations on the Serb side. It gives as example the Serb reaction to the trio's 14 working points. Yet during the negotiations the Serb position has shifted while the Albanians didn't cede an inch.
As I see it the Serbs have now a proposal that the Albanians can live with once they have swallowed their pride and suspicions. Now it is the turn of Albanians to provide a proposal that the Serbs can live with. This will mean much greater autonomy and maybe border changes.
At the beginning of the negotiations the troika indicated that they were open to talks about partition. But Serbia doesn't want partition if it means giving up on the Serbs south of the Ibar and the Albanians want Presevo in return. And then - rather than tackle those problems - the troika simply dropped the ball.
The present EU proposal is in my opinion just a proposal for ethnic cleansing.