I've got mine yesterday. Wish I got it on Friday, but fate has put me in bad luck, yet others got theirs on friday on god damn Super Saver delivery.
First Impressions:
The opening waste no time dilly-dallying, as you're plunged into the action in about seconds. Oh and somehow, you died. But that's okay, Cerberus revives you. Since the Illusive Man got billions of credits to spare, I want them to revive a Prothean. Or clone one. The text is bloody small, but I guess that's what I get for being cheap and not buying an HDTV unless it's given to me. Aside from that, when I plunged into combat for the first time, I instantly thought 'Gears of War RPG Lite', but the cover system is a good idea to copy. Ammo have been added and so far, I haven't really ran out of them... except for the Sniper Rifle.
Oh and I'm an infiltrator. There's more reason to be one, because Sniper Rifle is actually more useful than just picking enemies from a distance. Limbs and Headshots count for something. Combine that with a cloaking device and you have the best stealth fighter. Really, the Infiltrator is a tremendous improvement which won me over, where as in ME1, I preferred being an Engineer. Also, The Grenades have been ditched in favour of Heavy Weaponry. For me, I wholeheart it. Grenades in ME1 not only have a lack of accuracy, they also didn't have oomph and the person in charge of the Grenades at Bioware should be shot. I don't want to be pressing 'select' to detonate the grenade in a lag response of 3 - 5 seconds.
Now you have Grenade Launcher, which actually detonate. But not only Grenade Launchers, but Rocket Launchers too. Success.
Music so far have been on par with ME1, but the club music sound like they are... club music and not something that has been created in Garage Band with a few beats.
More Species have been introduced... whilst the current ones have more variety for once. In ME1, it feels like that Asari are calm mediators [unless been indoctrinated by Saren] and Turians are honorable race. In the second one, you have more species that don't fit a specific stereotype anymore. For once, I've met horrible, dishonourable turians, like on that Prison Station. The choices also seem to have more variety from what I've seen. But I love the Interrupt System. I actually punched that lass who tried to smear me in the first one. I think I reloaded it constantly, so I can see Shepard punch her over and over again. It's hugely satisfying. Now... Shepard, can you punch Liara over and over again.
tl;dr: Love it!
Would mention other things, such as researching your own weapons and mining planets, which are good additions. My only niggle is that I miss having Wrex in my party, since he was my favourite party member out of the first game.