That letter was a bit santamonious was it not??? And an epileptic dog?? Really, no need for that to be mentioned.
I agree with Strake, a short and to the point letter would have been appropriate...how do I know??? Well I used to work in customer relations for an airline, a good airline. If I had received a letter like this I would have already begun to write up a "sorry for the incident, please fly with us again, taraa" letter as I would have felt that there was just too much sensationalism and therefore possible exaggeration in the letter!
Also, I remember once sitting in J class on a flight to the states with the same airline I worked in Customer Relations for. I was very much in front row for disgraceful behaviour from perhaps the rudest individual I have ever experienced. He gave the cabin crew hell and really dragged down the flight for the rest of the passengers in the cabin. The crew were amazing in how they dealt with him even when the passenger sitting in the seat next to him wanted to punch his lights out. Anyways, a few weeks later I am sitting at my desk when suddenly a letter arrives in front of my desk addressed to the CEO (yes, its true, CEO's do not answer their own mail, they have whole departments to do that) telling a story of how this really nice passenger had been treated so appallingly by the evil crew of this particular flight. Straight away I knew it was this passenger and as a witness to the situation I knew that it was total BS what was written in the letter.
Now, I am not saying that this letter is BS but it is certainly not a way to write a letter to an airlines CEO!