It's just the new galaxy and system maps that's driving me nuts at the moment. You eventually plot a route with the clunky interface and then it only takes you part of the way. Some of the broken missions are annoying but I imagine they could get fixed. Of course, I could complain about the poor performance but I'll let everyone else do that
Not to mention, with the new galaxy map it no longer shows your friend's information such as Cmdr name, when you mouse over the friend icon. In all, the Galaxy Map looks and acts like someone in grade school reworked it.
The ships screen no longer shows what optional modules or the specific engineer mods.
When exiting a station, you no longer know which side is correct (missing green / red lights).
EDIT Correction. The lights are there. Just extremely faint and difficult to see.
Odyssey really is a huge step backwards for most of the the existing content.