I've been playing MM2003 for the psx2 all day, and I got to tell you, it is the best basketball game out there this year (that I've played which includes live2003 psx, NBA2K3 psx & Live2003pc).
It features the live03 engine with the addition of sliders which allows you to painlessly customize gameplay without tweaking hundreds of roster ratings. The strategy elements are incredibly deep. A bunch of quick call defensive options. Inbounds plays! In game injuries are included. Plus a full season and dynasty play. Really, other than 3 in the key (which I haven't seen called on offense with any Ea title this year); I don't see much missing.
NBA live 2003 is good, but if it had the sliders featured in MM2003, it would have been appreciated much more without tweaking. Ea's teams must be like the CIA & FBI, teams don't seem to communicate much, because everything I was looking for in NBA Live is right here in MM03.
That aside, if you want to play the best basketball of the year buy or rent this title (IMHO).