I tried the 10 hour demo, and...
Hrm. Mechanically it's an improved version of ME3, with added verticality thanks to the jump jets. Taking cover is thankfully an automatic response to pressing up against cover objects without binding a key press to it (and then sharing that key press with the sprint button.
Melee took a step back unfortunately. It feels... weightless and weak. You don't "Wind up" anymore, you just spam the melee button and that's all you get. You can do a neat AoE slam when you jump and melee but it's nigh impossible to aim and it lacks the unique class based flair from the previous ME title.
Gunplay also took a slight step back. All the guns I played with felt super weak. It often takes up to three...ugh, clips (yeah, we're still doing clips for whatever reason) to kill a single enemy in bronze multiplayer or Hardcore+ singleplayer. Also, there doesn't seem to be a way to command your squad mates to use specific powers any more, or if there is it was at not point made obvious. All I could do was mark a target for one or both allies and then they'd just suicidally bum rush the target regardless of enemy fire or how close to death they were.
The mako is back, and it's not complete shite anymore, but it lost its weapons which makes me sad. Of the two non-starting squadmates you run in to during the demo, both of them are introduced in an annoying and mediocre way, in that order. Peebee's intro makes zero sense and hits the player over the head with the "THIS IS A LOVE INTEREST" hammer by having her bumrush you from out of nowhere and then straddle your groin while trying to explain some bullshit nobody cares about. My first problem with that is why didn't my squad mates do their jobs and shoot the person making an aggressive beeline for The Pathfinder? One of them is an ex cop and the other is ex special forces, it doesn't make any sense that they'd just stand around with their thumbs up their ass.
The Krogan guys introduction is just... It's like they wanted him to seem like a tough badass but it's just lame and somewhat nonsensical. Oh wow, you killed one of those inviso-dogs, the ones we've been soloing for 4+ hours right about now.
The overall writing is ok, didnt really have enough to make a full judgement. The animations are inconsistent. The internet would have you believe that it's all atrocious all the time, but only in those cherry picked scenes of infamy is it ever THAT bad.
Multiplayer is mostly functional with a few glaring bugs and the same craptastic Peer to peer system from before. The biggest bugs I ran in to was the game randomly locking up and the games sound blowing out until you reset the program (also seemingly randomly). If you liked ME3 multiplayer this is mostly the same thing but even more frantic thanks to the ability to dash and superjump.