They can be summarized in the following points:
1. I know 2020 sucks, but did we travel back to 2012-2013 where instanced content had an owner and if they D/C or leave, everyone get's kicked out? And on a similar note, if someone accidentally leaves the instance or dc's they cannot get back in. Also requiring everyone to be in the same instance of EotN to start it is cumbersome, side effect of the way these old type of instanced content works.
2. The timer at the beginning of each mission, it should not make you wait the remaining time once the 3 tasks are completed.
3. NPCs get sneezed on them and they instantly die.
4. Rewards are little to none, especially with CMs. They are not worth the time it takes to complete them, and 0 replayability once you complete all 5 CMs for the achievement.
5. Escort missions are the worse in every game, and 2020 NPCs still have pathing issues and they backtrack constantly.
My 2 cents.