I thought it was an alright episode. Putting aside the emotion and lack of scientific background, I thought the giant magnifying glass was kinda funny looking at that those glesses looked rather good on Rory.
Back to the point, yes it was an emotional episode, not enough to move me to tears, but enough to wish something like that never happened again, for Rory's sake because it was tearing him apart. He just loves Amy so much.
As for the paradox...well...at least no one tried to divide by zero...