I was on Mucomyst years ago, but didn't get much benefit from it. If you can tolerate the smell (I've got noseclips that I wear for one of my other "stinky" meds) then it's definitely worth it to be on Mucomyst or a similar product. It's very important to be able to thin out that sticky mucus so that it's easier to cough up. There are some people who even drink the stuff because they've seen so much benefit from it.
These days the only mucolytics I'm on hypertonic saline and Pulmozyme. I was one of the people affected by DEY's saline shortage, so until I can get my hands on a new supply, I'm making sure to drink plenty of salted water, and I also take an expectorant at bedtime to keep the gunk in my chest from "pooling" overnight.