The multiplayer is as marketed in the demo, you can choose the 6 classes, and you gain EXP/Credits every mission. Then you use credits to buy booster packs. I average about 60k EXP a game, and about 15k+ credits.
All-in-all, the gameplay is sold. Same Mass Effect experience, but with survival. You're occasionally thrown a twist, a giant mech, capture/hold a point, or capture X amount of points. Others include eliminate target, wait for extraction, etc.
The full game will have more maps, more enemies, more customization, etc.