I recently read in a poll online that Harry Potter and the Chamber of Secrets(second book) was voted the least favourite of the seven Harry Potter books and I was shocked by this.
The Chamber of Secrets is one of the shorter books and could be easily read in one sitting. You can tell that this is one of the earlier books it seems to have a more light hearted and humourous tone that the later books don't feature.
But of course this book is not without its dark moments, especially with a monster on the loose released by the Heir of Slytherin. I feel also that the Chamber of Secrets is a key book to the following five because it introduces characters that feature later like Dobby the house elf, Professor Lockhart and Colin Creevey. The book also ties up vital links from the first book like learning how Hagrid was expelled from Hogwarts. It also shows the first signs of the link that binds Voldemart and Harry in that they can both speak to snakes.
I think that the majority of people have a later edition of this book because when the Chamber of Secrets was first released the whole Harry Potter frenzie had not began. So if you find a first edition...grab it while you can!