Haven't played as much Mass Effect 2 as I would like. But I have some things to say.
They made some really oddball gameplay choices. Like everyone, they're trending towards "packet gaming". The idea seems to be that we would prefer each encounter to be its own little game with no connection between them. Why they think we prefer this, I don't know.
It is like many other games of its quality, such as Doom III. At the end of a firefight, you are instantly restored to maximum. Your health regenerates in five seconds (literally), and you always find plenty of ammo for your guns. In fact, there is so much ammo, the only thing I've ever run out of ammo for is my sniper rifle. This is only because in order to make the fights challenging, they have to throw fifty enemies at you at once.
This style of game is becoming ever more common. They write attrition out of the game entirely. Presumably, this is so that they have a much clearer idea of how encounters will progress. In horrible games like Doom, System Shock 2, and Riddick, why, they had to actually design levels instead of designing encounters. That's why those games were so terrible! Man, can you imagine a game like Half Life 2 coming out today? Who wants levels? Pshaw.
This lack of attrition radically reduces the depth of ME2. Not having to worry about resources means that the game plays out super-linearly. Explore a level, hit a fight. If you lose the fight, try again. If you win the fight, no matter how narrowly, you'll be back and at full long before the next fight. This basically reduces the game to an adventure game, except without any puzzles.
ME2 has reduced depth along every category of gameplay except, perhaps, the ship navigation.
Apparently they took our whining about "guns in everything" to heart, because now there is almost nothing in the way of inventory management. Instead, you pick up endless Amounts of Elements, such as "500 iridium". While this is arguably better than finding guns in trash bins, it is a flat gameplay experience. It turns searching for loot into walking over money. Because, essentially, each element is simply a different kind of money. So 95% of the level's pickups are money and ammo. Worse, the ammo is "generiammo", to insure you never ever have to worry about pesky issues like managing your combat loadout. Or thinking.
I'm not sure why ME2 went this way. They have grossly simplified every aspect of the game. While many areas have been broadened (Shephard's armor), they are not very deep (only Shephard's armor, not anyone else's). They seem to have decided that players can't handle a game with any depth.
So I'm replaying Disgaea. Tell me when a game with some gameplay comes out.