I have just used the new treeshare functionality that allows you to pick the relevant spouse for each marriage. (I was updating Rootsmagic from Ancestry.)
The first marriages I added were for a person with two spouses, both already in Ancestry and Rootsmagic. This worked like a dream, where in the previous version neither marriage would have been linked to a spouse.
However, subsequent and much more common marriages were less of a success. The most common case is where a spouse and a marriage are being added to an existing person at the same time. Here, when you try to add the marriage, you get the response 'This person has no partner to add this event to' even if you have already 'added' the spouse in the treeshare dialogue. Instead you need to go through a two stage process, first adding the spouse and accepting changes (which removes the person and the new spouse from the list of people with changes), and then going back and then going back to the same person and adding the marriage.
This is obviously not ideal, especially when people including me have been commenting that treeshare is too labour intensive.
Personally, I think that the new function is an advance even so - you can only successfully automate things without causing problems if you can first get them to work without introducing errors - but it would obviously be good if a subsequent release could include spouses about to be added by treeshare as well as those already existing in Rootsmagic.