@iggy
Having started one (and then dropped out...) I'd say in most cases an MBA doesn't make sense. Exceptions:
1) you're going for a radical career change, e.g. you're a doctor, military, athlete
2) you want a 2-year career break/party and can afford it
The one highly valuable thing of an MBA is the network, especially at top schools
The most efficient hack to gain this network value is to start the MBA and focus entirely on making connections, ignore classes. Then, drop out after 3-9 months but stay in the same city. Continue to develop those relationships for the remainder of the degree without paying for the MBA or wasting time in class