It felt too bullet-spongey to me and I hate the bullet-sponge mechanic. Looking at the gear and skills, it reminded me too much of Division 1's grinding RNGs for an extra +0.5% crit.
As for the enemies, it seems to me a lot of them look like bullet sponge until you find out what their weaknesses are. For example, in the invasion mission, the robot enemies were very tough; but each had several weak spots; and all would drop if you could find and stop their controller.
Also, did you play alone? I feel it's a big difference, since even in a two-player coordinated team it's much easier to maneuver the enemy for their weak spots...