Ok, so on to the book. If I remember correctly, The Amazing Maurice and His Educated Rodents is one of the books aimed at children, like the Tiffany Aching series. It actually doesn't matter, because even though it's funny (and the humour is more obvious), it does have a deeper message.
Now, while this book is loosely based on the Pipe Piper of Hamelin (whoops, almost typed Hamlet), it's really about rats (the "Educated Rodents" of the title, finding out what makes a rat a rat (and what about those rats who can't talk or think?), while Maurice (the cat), unwillingly grows a heart. Meanwhile, Keith (the pied piper) meets Malicia (the mayor's daughter) and they try to have an adventure (well, Malicia does. Keith just happened to be there).
The rats are a really lovable bunch. There's Peaches, a rather bossy female rat; Hamnpork, the old leader rat who isn't that enthusiastic about change; Dangerous Beans, the thinker of the group and Darktan, an athletic young rat. There are a bunch of other rats, but these are the main four. Within these four, there are musings on what makes a rat a rat? and a change in the way things are run. This leads to one of those "old vs new" themes that could be old, but is actually really well done (and resolved in a very humorous way).
Of course, Maurice is lovable. In fact, he's the star of the book for me. He's very much like Puss in Boots, although he'd definitely deny the resemblance. But he's sassy (I'm sorry Maurice, I couldn't think of another word) and has a heart of gold despite his mean exterior. I especially love how he's a good negotiator, because look at his effect on people:
"Now he [the mayor] had the slightly hunted expression of anyone who'd been talked at by Maurice for any length of time. It said, "I'm going where I don't want to go, but I don't know how to get off". "
If only I could do that. I could probably get the 2/3 majority needed in a MUN conference. Or you know, get my teachers to give me better marks.
The humans, on the other hand, were a mixed lot. Keith is a sweet kid, but Malicia was so caught up in her story that she was rather insensitive for most of the book (I did not like to write that sentence). But everyone works out to be likable in the end so....
Personally, I don't see much difference between the "kid" and the "adult" Discworld novels. You should just read them all!