I thought it was an average episode, but interesting.
I didn't find the reincarnation explanation very believable, but that's probably just me. I don't know much about reincarnation, so maybe this is a stupid question, but does everyone who believes in it think that souls pass directly from the dying individual to a newborn baby? I know that is how a Dalai Lama is chosen, but it follows therefore that babies do not have souls until after they are born. If such a thing as a soul exists, I would have to believe that unborn babies have them too. Maybe they didn't mean to suggest that at all, but having the same birth and death dates, and the closing shots gave that impression.
I don't think they've ever covered reincarnation before, so it was good for them to find something different to base a story around.
Doggett and Scully still seemed not to believe at the end, but although we can say it's just a story, they didn't have that option, and I wondered how they could still not believe in it. The evidence was quite compelling and conclusive.
I wondered why it always repeated every 40 years, and not say 20 or 30 years later. Were the miners and the Sheriff originally 40 years old when the first crime was committed? If Reyes had failed again in this life, was she meant to kill herself?