Just a few notes from my adventures while transitioning/straddling the line between ArcGis Desktop and ArcGis Pro.
I imported a map that I regularly produce.
Remove Duplicates for Maplex labeling that had "remove duplicates" specified in Desktop did not translate. When I tried adjusting it nothing happened. Also, it looks like there is a pretty low limit on the distance you can input when using map units as your units of measure for the parameter in Pro. Looked all over and did not find any references that helped. Just for fun I decided to uncheck "use Maplex Label Engine". Saved the map, closed it and reopened. I then re-checked "Use Maplex Label Engine" and the remove duplicates for distance appears to be working.
Legend - my original legend was formatted as 3 column. When importing it reverted to a single column but the legend box covered the original area. Unchecked the "Keep in single column" box and all was resolved.
Symbolization - I have polygon data that needs some of its symbolization to appear on top of the other symbols in the layer. When importing the symbol display level was not transferred and had to be reset.
Save a lot. I know this should be a regular practice anyway but when working with an imported document, Pro seems to be particularly sensitive, becomes offended, and blinks out of existence. I had gotten spoiled with the stability of Desktop.
When adding new labeling, Tahoma is the default font. The Tahoma font does not include italics. This stumped me for a bit.
Hope this helps someone else. If nothing else I can use this post to remind myself!