I earned a MS in computer science in 2006, so things have obviously changed since then. However, I found it was hugely beneficial for me because my undergrad (also in CS) was very, very weak. As a result, I had the opportunity to realize my deficiencies in an environment where I could learn from them.

I spent four years in the MS program and, looking back, I could have done more with the time I had there. Even so, it was well worth it and opened a lot of doors for me.