That seems to be the consensus of most Might & Magic fans -- including me! I played 9 through once, and it was tedious, at best. I'd say 6 and 7 were my favorites (Fanfiction on MM7 is indefinitely on hold, but what I do have has several nods to MM6.)One thing I like about MM7 is once you get to Nighon, you can literally conduct business any time, day or night, since the hours there are reversed. Though, I understand that in MM8, some taverns are actually open 24 hours! (In 6 and 7, the taverns close from 2-5AM, or 2-5PM, depending on which area you're in.)
I may need to revisit MM8 sometime in the not so distant future...