DO NOT SUBSCRIBE!
I subscribed after reviewing all the cool-looking themes and plugins they provide. Since I'm not a programmer, I really liked how they said they act as an outsourced programming team.
Nothing works. The "guaranteed" plugins don't work or suck up a huge amount of bandwidth. The themes don't work.
Nothing looks the way it does in the examples.
You MUST be a programmer to use their products. Support consists of "Let me ask the person who programmed the plugin and get back to you."
And when you let your subscription lapse, any plugin you may still be using seems to generate a giant red message on your dashboard that says
"Please install the latest version of our free Update Notifications plugin which helps you stay up-to-date with the most stable, secure versions of WPMU DEV themes and plugins. More information »"
I know because it is currently showing on my website.
The last time I complained to them they offered me 50% off.
WPMUDEV.ORG IS EITHER A SCAM/AND OR COMPLETELY INCOMPETENT. STAY AWAY!