"Gonzo" is now my term-of-choice for describing Mystara. Thanks guys.
I'm a huge Mystara fan, to the point that I basically ignored 1e and 2e campaign settings (except for Planescape) and ran a BECMI campaign for more than a decade.
Having said that, even I have to admit there is no cohesive hook to the campaign setting. It is "everything and the kitchen sink". It's a homebrew world that has grown by patches and, unless you've already experienced a lot of it, I think it'd be quite bizarre for a new player. Previous posts should make that fairly apparent. Scottish liches and Spanish elves, a council of 1,000 36th level wizards, a hollow world, anthropomorphic everything (gators, lupins, tortles, rakasta, phanaton... it's a furry paradise), you name it.
Eberron and the Realms are not "anything goes" (...and for the record, that's a good thing in my book, because it gives those settings some level of consistency). If you cross the Thrane or Cormyr border, you would not expect to see French (and I mean FRENCH, not similar-to-French) wizards drawing power from a nuclear engine to assist their immortal master (a retired starship engineer) in his alliance against a dark-elven aztec-themed demon-god... and then you encounter some walking foxes with six-shooters.
I love Mystara, but I dearly hope WotC leaves it's glorious mess alone. Except for a 4e "Return to the Lost City". They can sell me that any day...