For me, loading times were not a problem. I did notice, however that for me they tend increase in time the longer I play. A restart of the 360 solves that, and I just installed both discs to my HDD to see if that has any benefits.
The biggest "gripes" I had were these:
1. Ally interaction> As someone posted above, there are not really enough times that your allies interact with each other when talking to another person, ESPECIALLY a character from ME1. I can understand that the "elevator loading screens" were kind of boring, but they were also very informative depending on the quests you have done and what allies are with you. I would much rather stand in an elevator and listen to my allies argue/joke/talk, etc and have the Galactic News (which is awesome, IMO) playing than have next to no interaction outside of loyalty missions, and having to stop at little TV screens to listen to the news.
2. The Mako. Seriously, I LOVED the Mako. I didn't always like going from planet to planet to find anomalies and resources (which were useless) but that thing was fun as hell. The new resource/mining system is pretty neat and effective, but INSANELY boring when you need to get a large quantity of resources (ie; ship upgrades). I wouldnt mind going planetside in the Mako to scout out a big huge source of Platinum or something. Anyways, the absence of the Mako or a ground vehicle in general was disappointing. In the Normandy Crash Site mission I was so stoked to see the Mako again, and I honestly thought that I could take it.... :'( And the tomkah's from Tuchanka were another close one. I SO thought that i would be able to grab one of those.
(on a side note -- why would they give you the option to talk to the Used Ship Vendor on the Citadel if he doesn't do a damn thing? I have not seen a quest associated with him..)
Which brings me to my next point
3. The Citadel. I did not like the lack of explorable area. At first I thought "Well its probably all damaged because of Sovereign". Nope. Its all fixed up, save for 1 Ward. I miss walking around talking to all the shop keepers and other people. The Presidium was the worst. When I fast-travel to the Presidium, I would think "The Presidium" meant the whole thing - not just one room...
Lastly;
4. Control sticking. There were too many occasions where I would press 'A' to get into cover, and Shepard would just stand there, resulting in me mashing the 'A' button and ending up with Shepard vaulting over the cover and getting shot in the face. This happens mostly after getting hit with a rocket (even though I'm behind cover) in which Shepard stumbles backwards. if you don't hit the cover fast enough, the enemy usually can hit you with another rocket..
I might mention the fact that with the Terminus Armour, you cannot modify it in any way. The reason I'm saying this is because I always wondered how the hell people could recognize me with my big ass, fully covering helmet on. (Also, the scene where you see Liara for the first time and she kisses you... Yeah. How does a kiss work THROUGH a helmet?..)
Other than those carefully detailed things, I liked everything else! Gets a 9.5/10 in my book because I'm generous.
PS: In the mission where you kill Morinth, the battle between her and Samara, my sound cut out for that whole dialogue between them... I checked my cables and they were fine.. Did anyone else have that problem?