Over the last three days I've spent a lot of time on a work of "young adult fiction" that I started writing about eight years ago. The process has been rather like dumping out a huge pile of pebbles, among which are scattered a few precious stones. Most of what I have written is dross, and needs to be discarded.
My main problem with The Amber Spyglass (the final volume of Philip Pullman's His Dark Materials trilogy, which begins with The Golden Compass) and with the third Harry Potter book (which I started but never finished) is that it seems like Pullman and Rowling just dumped and didn't bother with the much more difficult work of sorting, culling and paring down.
Of course it's been said many, many times, but I just want to join my voice to the choir: good writing is not so much good writing as it is good editing! A really good author is willing to drop extraneous details, avoids harping on pet philosophical ideas, and deletes unnecessary scenes or characters in spite of personal emotional attachments to them.
It's been a long time since I read the Chronicles of Narnia, but as I recall, C. S. Lewis did an excellent job in this regard. So while I may admire Philip Pullman's vivid imagination and narrative powers, I do cringe when I hear his trilogy compared with the (well edited!) Chronicles of Narnia.