Infiltrator is pathetic when compared to Vanguard.
Vanguard is immortal and deals insane amount of damage.
Hell, every biotic class is better than Infiltrator.
Apparently there are two people! O.O
I don't feel any particular need to exalt the Infiltrator, since I don't care what anyone plays, and all 6 classes are perfectly capable of wrecking Insanity with little effort.
But for the sake of mentioning it, the number-crunchers long ago established that Infiltrators have the highest sustained DPS and burst DPS, as well as the highest single-target one-shot damage. The exception would be multi-target damage, which in SP goes to adepts, situational as it is. As for survivability, most MP players learned a long time ago that Vanguard players believe themselves invulnerable, which is something of a problem. Not that a Vanguard can't be nearly impossible to kill in the hands of a skilled player, but that's true of every class, no more or less so for Vanguard. If anything, the best defensive ability in the game is Tactical Cloak. Whether you spec it for 12 seconds or 3 seconds doesn't make much difference, since 3 seconds is more than enough to drop aggro. Barring that, a Sniper Rifle receiving 120% damage bonus also includes an inherent slow-down effect that not only indirectly increases relative DPS, but also virtually eliminates the need to even use defensive tactics at all, since enemies die in groups before they are allowed to shoot back at you.
After reading hundreds of "Infiltrator OP Bioware nerf Infiltrators!" threads, I kid you not that I really never expected to see anyone say Infiltrators aren't OP compared to the rest, let alone claiming that they are pathetic.
But play what you like. It makes no difference to me what someone's favourite class is. I know the Engineer is weaker then most, but it is currently my favourite. I'll still mop up Insanity and Gold with Engineers, because once you know what you're doing, everything is OP.