I'm just wondering because a couple people have suggested that there have been nerfs to defense/parry/shield-use and that kind of aligns with some in-game experiences I've had. But my perspective is too narrow to know for sure if something has changed or if I just had some bad luck.
Codewise, no.
Obviously the new classes changed the composition of skill sets overall, beginning skill set, and starting values of skill sets, when comparing, for example, warrior to the heavy combat classes. These changes could have an impact on your personal experience, depending on what point along the power curve you are, how you've trained with the character, etc.