[eric_t]

It's a good roundup, but I think you missed the most compelling reason to do a PhD, at least it was for me. And that is that you get the opportunity to dig really deep into a problem for three year or more. And that is your only concern, no business crap, no customers, just you and your problem.

Also, the freedom of doing a PhD is great. Want to take two weeks to learn a new programming language? Sure! Want to take two weeks off and go surfing? No problem! In fact, some of my most important work on my PhD was done during one of these "diversions".

Finally, some jobs require a PhD. You may want to consider if that's the kind of job you want. Hard to answer that before you finish, though. For me the answer was a resounding YES!