I've learned true love when I switched to the Widow on my Salarian Infiltrator. Suddenly, cover and guardian shields were no obstacle. Heck, I got a couple double kills when I shot through one dude and hit another guy. So much fun.
To paraphrase HK-47, true love is shooting the head of a guardian and his buddy through his shield when he's obscured by smoke with a enhanced sniper scope.
P.S. I think I just got the Geth Infiltrator, so I look forward to wall hacking. I hate pulling up character cards after I've already received them. Gimme more weapon upgrades!