As a complete package, Mass Effect 2 is a better game than the first.  The technical issues are either gone or are very minimal, although I still had some gripes about Normandy load times.  The Mako segments are completely gone, as is the poor inventory management of the first game.  Graphics are much improved as well.   The story sets about the same for me; this game is almost completely character driven.  The first game had you with a pretty clear nemesis that you were trying to hunt down the whole game.  Mass Effect 2 essentially sets the ending point for you within the first hour of the game, and you spend the rest of the game getting to that point by recruiting your team and doing their missions.  Personally it's a wash for me, but I can understand people not liking the plot as much as the first game, as it's completely character driven, and lacks the grandiose space epic plot of the first game.   The game also seems to have a lot more humor, as well as cursing than I remember the first game having.  They've also introduced an "interrupt" system that I believe they touted for the first game but never really came to fruition.  In several conversations throughout the game, regardless of your character's alignment you will be given the option if you so choose to take an interrupt action; sometimes it is a Paragon choice, sometimes it is a Renegade choice.  Even though I went pretty much straight Paragon, I almost always did the Renegade interrupts, as they were usually hilarious and involved Shepard killing people in amusing and/or horrible ways.   The combat itself is much more action and skill oriented now, and everything in general has been tightened up and streamlined considerably, which makes for a much more satisfying combat experience than the first game.  I'm not sure why they bothered to add weapon ammo however; I can only think of one time in the whole game I ran out of ammo for a gun, and that was because I'd been using that one gun for a series of encounters.  The game throws ammo at you so frequently that I don't know why they bother changing it from the first game; perhaps it makes more of a difference on harder difficulties?
 
Where I have problems with the game is they addressed most of the original issues that people had by either minimizing them, or getting rid of them entirely.   For example, the Mako sections in the first game were kind of a mess with the Mako controls, and when you would find something on planets besides minerals, it was usually the same prefab building every time.  This is addressed here by completely removing the Mako; when you choose a planet, you enter a scanning mode.  Most planets can be mined for minerals via a scanner minigame of sorts, and these minerals are what you use to get research upgrades for your ship, amor, and weapons.  The problem with this is that the scanner minigame is slow as hell (although there is an upgrade you can get later that helps some), and more importantly boring as all hell.  At least with the Mako you were driving around a planet that at least sometimes looked cool.  It is also bizarre that there are so many planets you can mine.  I spent over 4 or 5 hours doing nothing but scanning in the first 15 hours of the game, before deciding to stop for a while, because my thinking was obviously that if they put all of this stuff here, we'll need it right?  Apparently not, as those minerals I had wound up enabling me to buy every upgrade for the rest of the game as they became available, with hundreds of thousands of each left over, AND I only mined about a third of the possible planets to mine.  I have no idea what the hell they were thinking here; the mining minigame is getting so much flak, but I think that if they didn't throw so much of it at you early on and spaced it out better, it wouldn't feel like such a grind that ultimately doesn't even really pay off or is necessary.   The upside with scanning though is if there is an sidequest on that planet, you scan for a location, then you fly down directly to the level, which are all pretty unique and different.  Most of them are still pretty short like they were in Mass Effect 1, but they're much more varied than they were in that game.   I am also baffled by the addition of a fuel gauge to the Normandy.  Ostensibly this would make sense to avoid having players get to farther out star systems than they may want the player to get to early on in the game, but even before you get the fuel upgrade (which I got at the very end of the game regardless) you can make it to any star system in the game and back to a fueling station without running out, so I honestly have no idea what the point was here.
 
The other big complaint that people had about the first game was the inventory system being a pain in the ass to manage (at least on 360).  So apparently Bioware couldn't figure it out etiher ,so they have more or less stripped the inventory out of this game.  Rather than finding and buying unique weapons and armor, you don't even have visible stats for most of these anymore; throughout the game you buy and/or spend minerals to research upgrades that mostly apply to your whole team, such as +x% to your shields, +x% Assualt Rifle damage, etc.   Most weapon classes only get 2 or 3 actual new weapons, and they're always a clear upgrade to the previous one.  Your have no management over your team's armor; they basically don't have any.  Shepard can buy individual armor pieces and customize the colors and whatnot, which seems great until you find out there's only about 5 different pieces for each part, and the ones I got in the first few hours of the game I used the entire rest of the game with one exception. 
 
One thing I also think that Bioware dropped the ball on was party banter; after Dragon Age's excellent party banter, you'd expect this to live up to at least that standard, but it comes nowhere close, with the party banter being almost non-existent.  The few that there are all are pretty excellent (particularly the one with Garrus and Tali in the Citadel), but it's a disappointment, especially considering how great the random NPC chatter in towns is.
 
My only final issue with the game is the by and large unimportance of importing your save from the first game.  Aside from some minor money and resource bonuses you get, it feels like the majority of the major choices in the first game are irrelevant.  No matter who your love interest was in the first game, you'll run into them in this game, but strictly as NPC's, and the game encourages you to have another relationship in this game anyway.  The Citadel in this game is optional as-is, and whether or not you let the council live or die was largely irrelevant.  The only one that really matters, and the main reason I'm glad I still had my save, was that by default without an imported save Wrex died in the first game.  Visiting Wrex in this game is fantastic, and I can't belive Bioware "canon" has him dead.  There are also a multitude of other small things you'll notice by importing where people might reference something you did in the first game.  This is all very neat, but has no practical impact for the most part.  Don't get me wrong, I definitely think it adds to the game and is a plus, but it seems disappointing that they didn't go any further with it.
 
That said, even though it probably looks like I crapped on the game for three paragraphs, at the end of the day this is one of the very best games of this generation, bar none.  The overall package is so refined and well done that any issues or complaints seem more more egregious than they are compared to the whole package.    
 
5 out of 5 stars
 
 
(Game beaten on Normal, Level 28, approximately 35 hours)