To me, MB plays nothing like IM. I find MB is MUCH easier, and is all about enjoying the theme and the sort of funny stuff. Every time I have played MBs, I have gotten to one of the mini-wizard modes. This could be from games set up easier than they should be, but even if you set up IM pretty easy, that doesn't happen.
I LOVE IM. I knew how much I loved it from the first time I played it at the pre-release party, and it would be the last game to leave my collection period. I also really enjoy BSD, for the same reason.
I have walked away from MB with credits on it.