Just finished the game! The last "level" is amazing!! I am at about level 45 when I beat the game (on normal), so the final boss fight is pretty easy, but you really feel like a badass, enemies got thrown around by my biotic teammate, it's really cool.
The game is not very long though, I got the "completist" achievement, and I spend probably about 32 hours, and I have been to every system and landed on every planets, I only go to the marked positions on each planet though (although I ran into some unmarked places by accident also).
A word of advice, if you are not micromanaging your teammate, make sure you let them control biotic by themselves, I had it set to defence only, and they are pretty useless, but once it's turned on, they become much more helpful.