I think there was a more significant improved with the gameplay between ME2 & 3 than most people seem to think. I suppose unlike most I've since gone back and played through ME2 again and no joke, the contrast was almost as drastic and the change from ME1 to ME2. Partly it's down to the new mobility stuff--rolling, diving, moving around cover etc--as well as the heavy melee, improved NPC AI, but mostly it the variety.
There's just so much more latitude in ME3: The weapon loadout brings back the best of the ME1 system without the encumbrance of the ridiculous inventory. The enemies themselves are more varied so now you have engineers and Geth Primes that drop drones & turrets and you have a good variety of reaper units. To top it all of of course there's much more in the way power combos. Being able to detonate biotics on a unit without first having to tear down it's shields was a welcome change. Powers like cryoblast, overload and sabotage have had their utility expanded so they can now slow enemies, weaken armour, stun and cause weapons to backfire.
^^ Singularity is MP only. Priestly confirmed it last night.
That's a shame as some of those changes looked like fun, but then I suppose adept Shep is pretty overpowered as it is....maybe not as OP as in ME1--my adept was so godlike it was hilarious!