My OMSCS experience was rewarding, but I think I echo most other commenters when I say it is entirely dependent on how much effort you can put in. Personally, I graduated in May 2017 after 2 years of study (worked full-time during those years), with a decently high GPA and a good understanding of the basics. As my undergraduate degree was in Mechanical Engineering/Math, it was interesting to get more involved with machine learning/robotics from the software side. If you already have CS experience, I don't know how much this would be beneficial over more traditional on-the-job training, but for someone who is diversifying/changing specialities, it was very useful. Though in my current role, its mostly used as a filter, so all the hard problems that encompass both departments seem to end up at my desk... Additionally, one of things about OMSCS vs a MOOC or self study is that because you have invested financially, you are more motivated to succeed. This can be especially useful if you are maintaining a full-time job while attending, as getting home from work to do nightly programming can be a challenge some days.