I would like to reply to a post from Tonya Frederic who said
"My Mom's advice has been the best so far : You will never regret
having a PhD, whereas you may regret not having one."
I think this is not necessarily true. While you must have a PhD for an
academic career, there are many positions in industry for MS
and BS degree holders. In fact, a PhD may be a handicap for some positions.
If a position is advertised for candidates with a MS or BS, most likely
PhD holders will not even be considered, even if the position requires
independent reasearch skills. I think this must be because PhDs command
higher salaries, and the company does not want to pay if they can hire a
good person with an MS. So, it is worth considering what kind of job you
want, than investigate the academic credentials required.