During the tutorial, aside from the obvious additions to the tutorial to cater for Shooter Mode, I didn't really notice that much of difference with the exception of the starting location of your character (Engineering for Engineering Officer, Sick Bay for Science Officer and the Armoury for Tactical Officers). I could be alone in this opinion but I believe the Armoury should become one of the rooms on player ships, if it's not already in the pipeline.
The mission itself - I'm still of the opinion that the Borg should be far fewer in number but stronger. Not just in this mission but in every Borg mission. Their drones should be able to adapt their forcefield to weapons fire which makes them impervious so the player has to rotate their weapons frequencies (say to get a 30sec window with which to deal damage) however it only takes a few shots to kill them - like in the TNG and Voyager series and First Contact. Their ships should forego shielding and be highly resistant to damage (armour - Tactical Cube) have highly regenerative hulls and stronger weapons.
As much as I hate it, I love the firepower available to the Unimatrix ships at the end of the new Borg incursions. If it didn't spit out the Probes and was just a pure battleship with the mentioned enhancements, it'd still take as long to destroy and it'd take more than a few ships with it. However taking on entire legions of Borg drones and an armada of Borg ships singlehandedly or even in a flotilla of 5 ships is pushing it. Despite advances in weapons and shielding made by 2408, I highly doubt that only five ships would be able to take out a Tactical Cube, 2 Cubes, 2 Spheres and numerous Probes in one engagement. But this is best saved for another forum, as I digress... The tutorial mission does seem to flow more smoothly which is a good thing.
The missions after being promoted to Lt look the same thus far with some obvious additions such as a secret side-mission that is specialisation specific and the cut-scenes (I haven't replayed or made a new Fed character so if these additions have been in for a while, I hadn't noticed). I only got to Lt 3 or 4 last night so once I've made it to Lt Cdr and can make an assessment on the DOff system I shall report back on my experiences up to that point, mission wise and feature wise.