Just bought it a few days ago and fired up World of Xeen after all these years. So many old memories surging back at once, though I was too young to grasp a complex game like this the first time around.
But before going too far into it, I decided to look into the earlier titles.
-I was a bit TOO dated for my liking. Couldn't even quite figure out how to go off adventuring.
-II wasn't quite as confusing, but if I can transfer characters from I, I'd better start playing that first. Still not sure if I could keep playing it, though.
-III is where I see a very clear predecessor to IV/V/Xeen, with a very similar interface that shouldn't take too much time to adapt to. There appear to be two more character slots where the clickable movement arrows would be in the Xeen titles, though, and looking at the character information screens, everyone also has D&D-style good/neutral/evil alignments absent from Xeen.
I think I'm now going to play through and beat III first before I go conquer Xeen and actually start off with VI.

Sounds like a good plan. III is a good place to start with for people who feel they will enjoy Xeen since it is fairly similar in style. I + II a bit too dated for many of us (myself included) unless you enjoy creating your own maps ;-P... Maybe someday I'll play through 1 + 2....
Xeen is an awesome game. I've played MM3-7 and Xeen is my favorite M&M game so I would suggest starting with III so that you aren't let down by going from Xeen to MM3.
The graphics are not dated at all for World of Xeen because they are meant to be cartoonish so VGA graphics are perfectly fine and fit the game well. If a M&M remake was ever made, I'd have to say World of Xeen should be it... although any developer willing to take it on better do it right and keep the charm of the game while modernizing the graphics, sound and interface.

also, MM3 is relatively short compared to world. so it's easier to start with it.

Actually, drawing my own maps is the reason I like the first 2 MM games, lawl.