I've grown to appreciate the MU eps for reasons like horatio83 mentions above. I enjoy studying the details. But the first couple time I watched them I didn't think they were fun, I thought they were awkward and boring (other than the opening credits which are pretty trippy, especially the Cochrane scene). The ENT MU eps look great, but they just don't work that well for me, though I've warmed to them with rewatchings.
I still think Mirror, Mirror is the best MU ep.
I still think Mirror, Mirror is the best MU ep.