Soreness is a result of an unprepared muscle. You feel soreness the day after. If the body is provided with sufficient nutrition, the body will make sure it never has to feel sore/wounded again.
Let's use an example: If you at day 1 benchpress 200, 5 times for 3 sets, then let's say, you feel very sore again the day after. Eventually the body will fix the muscle. The next time (within the first two week of course), you work out, do the same drill: 200, 5 times for 3 sets. The day after will feel less sore than the first time you worked out. Reason? The body adjusted to the stress.
The body is very adjustable. It only needs to be as strong as the circumstances requires it to. A guy working at an office doesn't need arms like a carpenter.
So I would say, soreness is a very good indicator on how your workout was.