Why is this night different from all other nights?

Parents in tears is the answer.
A few weeks ago, you may remember, I mentioned that Sachy had failed his trial of oats as a food. It wasn't too spectacular a failure though, he was only sick for a few days; and we had already ordered some oat matzah to be ready if he could have it.
And so, on the first night of Passover, Sachy did go ahead and eat his oat matzah, cognizant that he might get mildly ill, but willing to trade the risk for the mitzvah and the experience. I expected him only to take a taste, and I had definitely discouraged him and made sure he knew there was no need for him to even try it, but he was undeterred and in fact determined, since he knew he wouldn't likely get sick right away. He didn't eat just a bite, though; he loved it, and ate quite a lot. The next day he ate more, also eating margarine for the first time in his life, because one of the Passover varieties of margarine contained only oils. But I've saved what brought his parents both to tears Saturday night:
Listening to our 9 year old bentch (recite the blessings of the grace after the meal) for the first time in his life, in full, out loud, joyfully.
He did feel a little off the next day, and he's only eaten a bit more matzah, but he is so happy to be able to have it, even at a price, and even if only occasionally.
It definitely made for a Passover we'll never forget.