So our little one is very interested nowadays in Lord of the Rings online. He loves the map and that he can tell where the little arrow is pointing - and that there is water where he sees blue. He also has a character, that is progressing very very ... very ... slowly. This might be due to his total disregard for safety ("Ooh.. a cliff.. can I jump off it?") or his (ir-)rational fear of caves ("I don't like it - there's no sun in here - I'll go back to the river").
Of course we considered reading him the proper story, so he could appreciate it. And then we considered that maybe the Hobbit (being a childrens book and all) might be more appropriate. However, I argued (successfully) that things need to be read in proper chronological order to make sense, so we'll have to start with the Silmarillion.
It's been a while since I read it. Quite a long while, in fact. The main facts I remember were sentences that rambled on for several page - some of them spanning more than one page solely for the introduction of a characters name. You know... suchandsuch, who was known as slightlydifferent in the region of over there, who was widely considered wise in the valleys of overyonder where he was called this.
And ... erm... if it's not too much of a spoiler... when I opened the book, the first sentence I read was "There was Eru, the One, who in Arda is called Ilúvatar; and he made first the Ainur, the Holy Ones, that were the off-spring of his thought, and they were with him before aught else was made." 
And somehow, that does not seem appropriate for a four year old. I want him to listen to a whole chapter before falling asleep - not get annoyed and bounce around the bed after 30 seconds. So .. in the following chapters, I'll summarize the Silmarillion (until I loose interest, realistically speaking). For a four year old. Who loves monsters, and sharks, and dinosaurs, and who needs to grow up and beat up a caveclaw, so we can level in the Shire!
 Taken from: J.R.R Tolkien, The Silmarillion, Harper Collins Publishers, 1994, p. 15