I mostly Play Infiltration spec
Horrible DPS, would rather have a sent or even a Guardian dps. Too squishy to really do anything in a group setting. Doesn't bring anything to the table that another class can't do a lot better in both PVE groups and pvp.
The Concept is really fun. I feel very underpowered in any situation outside of solo gaming. Truth is though I do just as well if not better on any of my other toons (I've leveled at least one version of each character either on the pub or imp side.) I just don't feel competitive on my shadow. If I wanted to tank I would have made a Guardian or a Vanguard. If I wanted to play a ranged casty type (i.e. Balance) I would have made a sage. But no the only uniqueish tree to play on either a shadow or assassin is horribly out matched and out gunned in most if not all situations by better AC's. Burst was ok until endgame (this mainly do to always being a higher level then the instance was rated for in pve) and in pvp it just doesn't compare to other AC's burst/utility. I can play smarter in pvp but if I was fighting me playing an operative, me playing the operative would win when it comes to bursting and quick kills. I gave up trying to play rated, its all very depressing, this was the class I latched on to while waiting for Tor to come out and now I just feel let down.