The mission/plot was a stupid premise (but yeah, Walters). It was obvious they felt they must include combat, so they cooked up that. I would have preferred they scrapped that entirely and just focused on the fan service bit to be honest.
That being said however, I did like the concept of everyone coming along and actively taking part in the mission, rather than off-screen stuff like in, for example, ME2's suicide mission or ME1's Virmire base infiltration. It always annoys me these days that party-based games are so ridiculously small. You have this large group of maybe a dozen people but only let 2 of them tag along when you are inevitably going up against far superior numbers? Fair enough a combat unit may be most effective at around 5 people, but you would sure as hell be sending out the rest as well in additional squads.
For the fan service stuff, there's not much to say. There were some quite funny moments, but I thought the party element probably dragged on too long and the individual hookups were too short.