Yes, I would use it even if it wasn't free. We love it around it.
I must confess that I do supplement, but if money was tight (well, tighter than it always it), I would stick to just MEP. The only reason I supplement is because 1) it's fun to pull from various different approaches, and 2) I just can't help myself. I'm a supplementer. And the kids like it, so why not?
But, yes, it is a great, complete, standalone curric. I simple cannot recommend it enough.