Having been a year old when the series was first released, I wasn't going to be able to read it, much less appreciate it, until after it was already over. So I wasn't easily going to start at the beginning.
My non-English-speaking grandfather bought #19 The Departure for me as a present when I was about six. I'd never seen the series before. I assumed it would be about a fairy or something...?
Anyway, I tried reading it and had no clue why a bunch of people were fighting and why one was melting out of an elephant, let alone the alien invasion stuff since that particular book doesn't have the typical "the Yeerks are here" opening. I gave up after about a chapter.
A few years later, I was bored and decided I wanted to read something and picked it up.
eight year old mind=blown
...and I was never the same.