Where, when, and how.
Where: The school that you attend.
When: Straight out of college, or after working for a while?
How: Online or in-person?
In my neck o' the woods, there's a general sentiment that the MBA degree is more valuable (i.e., marketable) if you get it after already establishing your success in the business world. The route of going to business school directly after college is associated with the suspicion that you couldn't get a job, and still need to come up to speed in a business environment.
The people I know who have done this are mostly techies of some sort, and the conventional wisdom seems to be that business school is "hard" because of the math involved (finance and also some basic statistics), so if you're good at math, then it's not very hard.
From what I can tell, online programs from prestigious schools are gaining acceptance.
I don't know if the rule of thumb about graduate education applies to MBA programs: Don't attend grad school unless somebody else is paying for it. A benefit of getting an executive MBA while working, is if your employer is willing to reimburse you.
