Underwhelmed, I think Prologue: Earth isn't a very good mission from game design perspective and because of that it leaves much to be desired. I first played the game in June about a week before the EC (my first completion was with the vanilla ending). Before then I had heard that there was controversy about the ending but I didn't know the specifics and pretty much everything was tempered with, "the other 95% of the game is great" bits. When I did beat the mission I felt a little sad for leaving Anderson but other wise it was completely, emotionally flat and started the game on it's left foot. Unfortunately, though this would continue to be my impression for most of the game.
It starts off well enough for the first couple of minutes up to the part we see Shepard and James. There's quite a bit of exposition laced with the troubling binary dialogue prompts which would be fine but it leaves more questions than answers for all players on the New/ME2/Arrival spectrum. Then there's the uninspiring Alliance Defense Committee scene and Shepard is thrown into action. The problem here is that there isn't much to engage a player. I feel about as disconnected as Shepard running a top white sterile buildings, away from the humanity below. This is supposed to be the game's hook but it quickly degrades into slight confusion and a visually clunky tutorial mission. Then we get the kid. I can see how the child could be effective but I saw him as a representation of what was wrong with the emotional stakes for the prologue. It was overly hamfisted pathos. The writers basically hung signs around Earth and the kid saying, "You should care now." complete with sad piano music, when at the moment I felt like some ambient action beat because I just had to empty a couple of thermal clips to get the Normandy to come down (this took me about 10-15 minutes before I realized I had to empty all the ammo, which. did. not. help).
Mars is fine, with what I thought was a cool introduction for Liarc (although I was distracted by the increased sexuality theme that haunted the main female characters -- did everyone get breast implants instead of preparing for the Reapers?). Which was great because I had to do the entire mission over again because I had a DLC pistol which was useless for the Eva Core sequence (this did not help my impression). The next part of the game was overly filled with dry exposition which made me restless, by this point I still felt like the only way the game was engaging was through the gunplay.
Edit: By this point I felt like the game was very much an unpolished straight up shooter. The plot felt mostly like people telling me to go different places and shoot different things, only they were being long winded about it.
Not Palaven was a disappointment as I thought we would be getting culture and world building but just ended up with a stark moon. The shot of Lake Fire on Palaven at the end is what I think one of the more memorable visuals of the entire series but I felt it didn't justify fighting on barren rock. Then EDI's body happened.
My next mission was Grissom Academy -- personally my favorite mission in the game and one of the top in the series. This mission made me feel a lot better as I got to see Jack again, I got to go through some varied gameplay, good pacing, emotional stakes, some world building; so much so much good stuff that not even Cerberus could bring me down. I loved this mission and it remains a highlight of every run.
Sur'Kesh was a very important mission. This mission started off very well. We get to walk around, learn a bit about the Salarians, got great exchanges between characters... but then Cerberus invades and it all evaporates. Given the poor justification for their appearance (ie none) this part is very frustrating. A large portion of the genophage arc felt like this. There were very good moments but there even larger moments that failed to engage and just had to be played through. Ultimately, while these parts are forgettable compared to moments like the end, playing through them isn't exciting.
The two missions with the Primarch's son are like this. For the first you're told to rescue the son of a guy you just met, then you're thrown into dark brown corridor for half an hour until you get to the exchanges between him and the crew. Then you have to deal with the bomb after another series of hallways. The cutscenes at the end are okay enough but they do not justify all this filler. When I first played through these missions I felt cheated. The Rachni queen mission left me frustrated as the imported Shepard had destroyed the last one. Priority: Sur'Kesh left me underwhelmed until the end. I felt like the tunnels and the temple reveal were supposed to be inspiring but the lack luster art direction and overly brown pallet prevented them from being so. By the end though I did shed a few manly tears.
More ranting to come...