MBA's are great for 2 things:
1) If you are not a business undergrad, or have not picked up these skills on the job, then an MBA is a great way to get a solid business understanding that will prepare you for another type of work.
2) High ranking MBA programs attract serious talent, and then network that you acquire at a respectable university is also very valuable.
So really, if you want to change jobs, and want some credentials and training and/or want to fill up your linkedin profile with some future superstars, it's a worthy investment. Otherwise, it's probably not worth the time or money.