WPMU DEV is essential for anyone looking to get the most out of their use with WordPress. The ability to have so many different customization and functional options available to you is very beneficial. With WPMU Dev, you get all these under the same roof! So, whenever you need support, their top-of-the-line support team is there with the solutions to your problems.
I have had nothing but possible positive experiences with WPMU DEV and I can't foresee why that would change.