The simple act of shooting feels so much better. Headshots do extra damage, blown away limbs force Geth to a crawl, and the pistol is no longer the ultimate weapon of doom.
Further upgrades - biotic bonuses, damage multipliers and shield improvements - are all automatically applied once they're researched, whereas in the first game they had to be manually applied to each party member. Ammo types are now tech powers, and need only be triggered once per mission per gun. It's a philosophy that extends to all of Mass Effect's fluff - the fat has been cut away and dumped, leaving a lean and trim RPG that never frustrates. Ever.
Mass Effect's elevators - clever cover for extended loading - have been removed in favour of proper loading screens which show you the journey you're actually making, whether it's travelling from engineering to the captain's quarters in the Normandy, or taking a taxi ride from one part of Illium, the lawless Asari colony, to another. We quite liked Mass Effect's elevators, but not enough to rue their expiration. In any case, party members now banter as you explore Mass Effect 2's many wonderfully realised worlds, and you can get the news from kiosks and PAs.
Perhaps the main gripe with Mass Effect was the lack of a sense of exploration; off the beaten track quests were repetitive and recycled the same structures and environments over and over again. In Mass Effect 2, you certainly feel as if you can explore more of the galaxy, even if the number of planets you can actually land on has been reduced. Now, the wonderful Galaxy Map has been refined to allow you to manually fly the Normandy from system to system, consuming fuel along the way. When you arrive at a planet, you can scan it by moving a reticule slowly around its surface. Not only is this the main resource gathering mechanic - itself a strangely addictive and engrossing mini-game (one that held us in a trance-like state for over ten hours) - but impromptu side missions also reveal themselves here. These side missions are all different in some way, be it in the background to the mission, the building it takes place in, or the enemy you're up against. Some don't even require combat.
Another benefit to this new system is that the Mako Rover - so reviled by fans of the first game - is nowhere to be found. Day one DLC promises driving of some sort, but the truth is that the Mako is gone for good (we're not sorry to see the back of it). Should we have expected a galaxy full of planets on which you could land and explore? Of course not. But until we actually played the game for ourselves, we dared to dream. This is BioWare, after all.
There are many other improvements, more than we can list. The cutscenes are more dynamic, edited breathlessly in the MTV Generation style and brilliantly complemented by the new Interrupt system. The frame rate is locked at 30FPS. Textures hardly ever pop in, and there's no tearing. The new and improved Normandy is a bigger and busier place, spread out over four floors. The classes are now more defined, and feel remarkably different. Squad control is about as good as it's ever been in a video game - the contextual d-pad system directing party members as if they were hardwired to your brain. The cover system, which now involves a button press, is only bettered by that of Uncharted 2 and Gears of War 2. The graphics - a jaw-dropping fusion of Star Trek lens flare, early 80s sci-fi and the best god-damn vistas your eyes ever did see - are almost too good to be true. And the new hacking mini-games are even - shock horror - fun.