There seems to be no ready-made tag for discussions of the pros and cons -- see, e.g., this question -- of the Mathtime Professional fonts package. I know it doesn't come up very often on TeX.SE, but it's actually a rather nifty package (everybody's reservations about superwide accents and 5cm-tall summation symbols notwithstanding).
I've noticed that the recently released
newtxmath package consciously uses output from the
mtpro2 package as a yardstick to measure the quality of its own output (and, importantly, how much better
newtxmath is than
Much more information about the Mathtime Professional font package may be found at this site.
What do others think?