I think the book is an absolutely essential read. Regardless of weather or not folks like the final chapter, the bottom line is this is Burgess' story, and thats what he envisioned. If I recall he said something along the lines of "why bother telling a story if your main character is to remain stagnant, have no growth, and have no point" which is a classical english school of thought, not straying too far from fictional traditions
Whats most impressive, and amazing, is that the dude basically invented a language for this novel! and though your befuddled at the start, by the end of it, you've completely learned the language of Nadsat!
Anyone whos a fan of the film, read the book, if nothing else, you'll develop an entirely new level of appreciation for the film, and get a one of a kind literary experience!