So I'm still playing the multiplayer demo, and after only having the salarian Infiltrator and turian Sentinel for all these weeks, I finally unlocked the asari Adept and the quarian Engineer last night. The quarian's okay, but holy crap is the asari awesome. I outfitted her with a sniper rifle, and leveled Stasis up all the way, and it's headshot city with her!
ETA: And, not more than two minutes after I posted this, I just unlocked the krogan Soldier. At last!