Absolutely was! And not because it was some ridiculous OP tree either. It was popular because it was new and players like new.
Early on when Vistani Versatility affected any and all weapons there were definitely some exploit builds focused around it before that was fixed. But as a whole, even then, the tree was pretty far from OP and really only optimal for dagger rogues or people wanting a good chunk of early power while leveling a dagger melee.
This whole Inq thing is on a whole new level though. It's not only the best single tree in the entire game but it's also a universal tree and can be set upon any base class to provide an immediate dose of stupidly OP.