Coming from an acting background, I personally despise ADR. Sometimes, like today, it is a necessary evil. However, with that said, the audio specialist's who make it work are amazing at what they do, and at what they can endure.
On Hollywood films, ADR is par for the course. But, something is always lost in the translation. The level of disconnect from the initial scripted (or not) words, to the performance, to the sterile soundproof booth is the grandest of artifice. I cringe whenever I find myself in that situation.
However, my experience tells me that it's never as bad as it is when you hear it, raw, out of the monitors at the sound studio.