I'm about 4 months in to my MBA program at a tier 2 school (University of Utah). I've enjoyed it for what it is, a chance to add to my knowledge base, pad my resume, and maybe even offer an opportunity for a career change (BS in Electrical Engineering). My employer is willing to foot 50% of the bill so I thought I'd take them up on it. Depending on what you do and where you want to go, this is a good choice or a perfect waste of time.
I've been an engineer for almost 10 years now and I've pretty much hit "Senior" on any engineering job title I can have. To move up to the next step, I believe you have to move up in to mangement and supervise others. An MBA is a good way to do this. In addition, I do see myself starting my own company one of these days, and if all you have is a technical background like I do, you'll never be exposed to the business side of things. Now I understand a lot of aspects about business that I never considered being a cloistered engineer. Even if I choose not to do my own books or whatever, at least I know that if I hire somebody, I'll know if they're cheating me or not.
Overall, I'm happy with the decision. The only thing I may have done differently is trying to get in to the joint JD/MBA program, but then again, I'm busy enough as it is. 🙂