I've been in the tech business for 30 years. I can tell you this much - you're obviously going to get a lot of conflicting discussion here, but keep in mind that's because each of the respondents has different job goals.
Generally the master's pays off in the long run. It can get you an additional $20k/year initial salary, but it's more common to see around $5-10k. So you may or may not see an ROI in the first couple of years out of school, and that's a goal you'll have to consider. But you will see an ROI if all other things are equal, and it will make a bigger difference in your future, everything else being equal.
More importantly, it opens doors. Many jobs at the supervisory level require or highly prefer a post-grad degree. This does vary by region, so doubtless you'll get arguments to this. Public sector, such as government jobs (NASA, state and federal jobs, military civil service, and public sector colleges, for example) typically require master's degrees for higher level positions. Notice I said "typically." Some require Ph.D.s.
So the question is more one of what do you want to do with your life? If you'd like to be in management some day, you better your chances with higher degree. It's much easier to get the degree while you're still in the college routine, and it's much harder to fit it in later in life. I got mine right after my bachelor's and my wife got hers 20 years afterwards, even though we were in college together. It took me 1.5 years to complete, and it took her 5 years. Evening and weekend classes, much tougher when you have a job and kids. Plus, read back articles in /. and you will see that your brain develops and learns faster while you're still young.
Finally, getting the advanced degree will teach you things you won't learn quickly in the career field. I've had lots of young grads come to me with wonderful new things they had developed, which were really nothing new. How new can round-robin process scheduling be? I have to hand them a book and a reading assignment to show them that they're 40 years behind the times.