If you know anything about the previous games, it's feels like the combat and planet exploration of Mass Effect 1, the space exploration and relationships of Mass Effect 2 and the biotic combat, UI and multiplayer of Mass Effect 3. Now that might sound like a pretty great game and it would've been but you quickly realize that BioWare got everything in between wrong and somehow turn what should've been a great game into this embarrassment to the Mass Effect franchise.
First and foremost, I understand the decision to take out paragon/renegade, what I don't understand is the decision to take out face to face conversations. I say this because 7 out of 10 conversations are conducted at the most ridiculous angle or with the person's back turned to Ryder. Sadly though, this isn't all that bad of a thing considering that the 3 out of 10 conversations that go right force you to look at the worst faces in video games. From the lips to a bone-spear beard, everything is wrong with the faces, everything.
Second biggest issues is the size. The size of the planets are about the same or bigger than the maps in Mass Effect 1. The opportunity for exploration is immense making the transportation all the more important. Unfortunately, BioWare decided to solve the problem with the Mako 2.0. Granted, the Mako 2.0 (NOMAD) is fantastic compared to its predecessor but it will certainly cause some serious flashbacks.
Finally, the only saving grace of this game, is the combat and boy is it great. Mass Effect does a decent job of making the open world combat interesting by giving you worlds that feel a lot like Borderlands/Destiny while you fight your way through half Halo, half Destiny-ripoff aliens who are using "Prothean" weapons for some reason. It's fun and the environments you fight in make it even better.
Unfortunately (and I hate using that word so much with Mass Effect), combat, conversations and driving on/exploring planets is 99% of the game and they messed up 2 of them. Were it not for the fact that the combat is great and the crafting brings back a nice feel of Mass Effect 1, my score would be even lower. Despite the bad, the game is mediocre and worth playing just so you can say you're a real planet conquering human who has a complete disregard for other alien species but maybe wait until the game is on sale.
p.s. I've played the multiplayer and so far everyone sucks so it's not a whole lot of fun unless you party-up. I'm not going to knock the game on that just yet though because presumably people will figure it out and it will be as fun as Mass Effect 3.