Is soreness a sign of a good workout?

No. Soreness mostly measures novelty, not quality. A brand new movement leaves you aching for days; the same session two weeks later barely registers, yet builds just as much strength. Chasing soreness just chases newness.

The signs that actually mark a good program are quieter: doing one more repetition than last month, carrying groceries more easily, climbing stairs without thinking about them, resting heart rate drifting down.

Train hard enough that the last repetitions feel like work, expect some ache when a plan is new, and judge the program by what you can do in week six that you could not do in week one.