Some of them are noticeable, some are not. A good example would be inquisitor vs consular procs. With the inquisitor you get well defined visual procs aswell as a clear sound cue, but with the consular the visuals are just faint light glows that are almost impossible to notice in the thick of battle and the sound portion of the effect you can only hear if you're alone on the training dummy.
I like this system better than some auras around my character but it could use some improvement because it's not equally well done on every class.