Yes, Assist Mode performs the battle rotation and heals party members automatically.
The most important difference is that you remain in full control of your character.
You can move, dodge, change targets, and even stop for a chat. Miqobot will do her best to help you on the journey and provide the most comfortable experience.
You can enter any dungeon, trial, raid, or Eureka instance. As this is an attended Miqobot mode, all location restrictions are removed.
You can find the detailed explanation as well as basic guidelines in the main beta thread: [Beta] Combat