It was a fun game. I don't want to spoil anything, so I'll try to be careful but am willing to remove the review if I reveal something I shouldn't.
The atmosphere was simple, but used to great effect. 5 stars there. Even the fact that the words appeared slowly added to the suspense--and this is from someone who abhors that effect.
I like Noel's mocking tone. He writes in one of the letters that the detective almost caught him, though of course you can't believe him. Nobody takes the time to write "AHHHhhhh!" so to speak.
The first puzzle was by far the hardest for me because I thought that part of the clue was one of those red herrings that the intro mentioned. Incidentally, were there any red herrings?
The "riddle me this" answer is a bit odd, considering that the question is "what do I like" rather than "what am I?" The confusion is in changing what "I" stands for.
Lastly, the fire in the alternate ending doesn't make much sense--where did it come from, if you assume that what the perp is trying to portray is really what happened.