I feel inclined to answer this thread, but I sincerely don't want to flame. This is my opinion, and although I am very much aware that there are others who share the same opinion, I can't talk for them, I can only talk for myself.
To begin with, i did like and enjoy ME2 very much. I still do, I've imported my femshep, I've made an ME2 maleshep and overall the experience was enjoyable. The graphics were absolutely stunning, the plot was captivating, the ending a proper ME3 cliffhanger, the epicness was right up there, no shortage of attitude, couldn't I have the varren as a pet aboard the Normandy lol ?

But, there are so many "little" things that I didn't like that I can't just ignore. So, here goes.
1. Although I liked the shootemup, i found myself looking for clips with my soldier character. So much so that I didn't really enjoy the soldier and imported the shep again as another class, which was far more enjoyable. My maleshep who was a sentinel had the best time ever, and hardly ever emptied a clip. I just see a discrepancy there that might have needed some more attention before release.
2. I don't mind the planet scanning, I actually found it quite the mind-melter, when i wanted something to do without lots of action. What I didn't like at all was the lack of funds. At some point I had billions of resource and not a penny to my name, couldn't buy more upgrades for research, couldn't buy anything, not even a fish! The game simply did not provide for money making! You have the most advanced ship and gadgets at your disposal (climax climax) and... you can't buy them (epic fail). There's no armor to sell or weapons or mods or anything useful to other people, and Shepard and the Normandy are basically a big money gobbler! Real thumbs down on that, seriously.
3. The exploration bit was indeed missing alot. The citadel should have been bigger, and you should have been able to get the feeling you walk for a five minute distance ingame. I never insta-travelled much in ME1 anyway, because the walking from place to place served towards the immersion in the world. Just having Shepard insta-beam to and fro the Normandy like captain Kirk isn't enough towards that end. "Scotty beam me up" doesn't really work well outside Star Trek.
4. The game was forced linear. My ideal was to gather up all the crew, as I did in ME1, and then go exploring the galaxy, land on planets, go mining, so on and so forth, but as soon as you get the first two, it FORCES you to go on one mission, then again after the rest, then again so's to be able to survive the suicide (give us a break) and then again as soon as you get Legion, provided you don't want to butcher your entire crew, up you go and game over. Yes I know you can do all those things afterwards, but I don't want to do them afterwards, there's no point, from my pov. Anyway, that made me juggle abit, between quests, side quests paragon/renegade options and so forth.
5. From a female shepards pov, the ME2 romance was a total fail. If it wasn't for Thane, who sorta saved the day basically, it's a joke. Anyway, I decided to stick with my ME1 romance, Kaidan, who, appears very briefly very unexplaindly and very very VERY lamely on Horizon, and basically gives you the feeling the devs are telling you "stop moping and go shag Thane". I don't disagree with his pov but it could have been done a lot better, since you KNOW we have an ME1 romancing option in the character profile, cause it doesnt do that if you were just friends in ME1, elaborate a bit, don't ****** downwind and tell us it's raining. Besides that, I tried to engage in conversations with people and I ended up romancing half the crew, and/or get reactions along the lines of "I'm like you Shepard I don't do women" (Jack) or Mordin's I don't dig you bit. All that just cause you want to talk. Not to mention the UNFATHOMABLE sleezy "i just wanna talk sweetcheeks" attitude femshep has towards Jacob. Hint: we don't all go around with our brains in our crotch, and not all f/m interaction is sexual. Alot of grief regarding this point, but since I've elaborated on that elsewhere in the forums, I won't go on here.
6. I liked the loyalty missions well enough, I understand their usage, but I don't agree with the loyalty handling. I like DAO better where companions agree/disagree with your actions and thus formulate their like/dislike accordingly. The ME2 one seemed like a cheap emotional tradeoff, "do right by me personally and i'm your dog", sorry it just doesn't cut it role-play wise.
7. What in God's Good Graces gives with female Shepard's macho-ness? I agree she's been a marine since ME1 and she's had a roughness about her, but femshep behaviour in ME2 was distinctly male, so much so that at times I caught myself wondering if she was designed to be lesbian or just happened. I understand having one common behavioural model for the player character, and I understand it would be far more hassle creating different patterns for male/female, but guys, really, male and female DO have differences, and they are completely eliminated here. I mean, sure, go ahead and headbutt Krogans all you want, I'm with you there all the way, but when she needs to show some charm, femshep has the charm rating of an oyster. Jack was at times more feminine, and it sort of pisses me off that Miranda was the "sex goddess" in there, well, no, mate, you're wrong, when it's a femshep around, Shepard is the sex goddess, and excuse us for wanting the ego boost. More grief there.
8. Companions-wise, epic fail. Unless you're planning something absolutely SPECTACULAR that will leave ME1 importers speechless and in tears in ME3, which I very much doubt tbh. Ashley and Kaidan were very strong characters in ME1 and despite the fact that you do sacrifice one of them, or maybe exactly because you have to sacrifice one of them, the other takes a special role in the team from then on, if he/she hasn't already, as a lover. And you just ditched that, almost like it never happened, never even gave an option to choose whether or not we want to have this special friend with us again, no, and we get stuck with uselessness in repetition. The only distinct characters ability-wise in there were Garrus (and i'm thankful for that, Garrus rocks), who is also not entirely unique cause of Thane, and Mordin. And also Tali, but then you had to introduce Legion. Jack and Samara are more or less on the same range as Miranda, and I just got the feeling they were so many just cause the maleshep needed somebody to shag, cause frankly Samara would have been more than enough as the team's solo biotic. The cheesy dog fights between Jack and Miranda were rather cheap, but i can understand malesheps need an ego boost too. The Krogan was, bluntly, indifferent in his uniqueness, I liked his whole story but couldn't relate to him no matter what. Jacob was plainly useless and pointless. Even his loyalty mission is a fail. His abilities are a mix any Shepard can eaily cover, and he's a weak character compared to the others. So, (for the new ones) Thumbs down for: Jacob, Miranda. Thumbs up for: Mordin, Samara, Thane (and i personally put Jack here too). I reserve judgement on Kasumi and Zaed until i have a complete and overall perspective.
9. The SR2. Perfect ship. Absolutely gorgeous, and I love it, customisable, same goes for the armour, thumbs up for both, fish and models and hamster and all and then you give me the emtpy cabin with a huge double bed and a holo-photo on the desk, and a notice everytime I get in the elevator saying: commander's cabin, crew members: none. It kinda urges me to use the F word. Anyway, this links to a previous point I already discussed so i won't get into this any further. Just keep in mind that this isn't the torments of Tantalus, it's a game, lighten up a bit.
10. Last, I have a bit of an issue with story continuity. Wrex: good continuity, you go there, meet him (provided he's still alive of course), he explains, you get the sense that you're covered by what he says, how he's been, what he's doing. Liara: not good continuity, you go to her, she's not Liara anymore, she's somebody looking like Liara. She treats you like a stranger, she doesn't say anything to you, you get the feeling that there's something going on somehwere else you haven't gotten to just yet. I know that this is in a novel or whatnot, and I find it tacky. I know this is a franchise and it's about money first and foremost, and this is a way to further monetary gain by making people buy extras, but it's a cheap and insulting way to do this. Give proper story continuity ingame, respect your audiences, and then they'll feel more inclined to buy the Star-Warsy kind of 'go buy the novel to know more" stuff. Botch.
Overall, as I said in the beginning it was an enjoyable game, which I will keep on playing over and over again, cause I liked it, but, I can't overlook the grief, and there's lots of that. I sincerely hope the focus falls back to the depth and detail a real RPG requires in ME3, although I don't think it will, given the MP rumours going around. I think we can see that this isn't going to be what the roleplaying minority wants, and it's just going to get more "normalized", in accordance with other popular titles. Let's see. If I'm wrong I'll buy everybody a round, is all I can say.

I apologize if I rained on somebody's parade with what I said.