According to the book's copyright date, this is the 1st book in the 'Chronicles of Narnia' series, though it's 2nd in reading order (as numbered by the publisher). There's a great article about this in Wikipedia (http://en.wikipedia.org/wiki/Narnia#Reading_order), but after reading the whole series, I'd strongly recommend the copyright order, as in my oppinion, 'The Magician's Nephew' answers too many questions and spoils the whole magic of Narnia.

As I read this book AFTER watching the movie, the plot and events appeared rather unsurprising, so I'd also recommend reading the books PRIOR to watching the movies, because a) you'll be able to enjoy the book fully and b) you'll be able to follow the events in the movie much better.

As for the book itself, it's quite entertaining, though honestly, it didn't meet my expectations, but then I'm probably too grown up (23 y.) for this kind of fairy tales; the book somehow seemed to me too unrealistic and unbelievable.
Besides, all the Christian parallels really annoyed me (though if you're not familiar with Cristianity, you won't notice them), IMHO, the whole series would have been much better without all that proselytizing. The movies seem to cope with these to challenges quite nicely.

There's no denying that kids up to 10 years old will definitely love this book (and series), but unless you actually are up to 10 years old, or very much into Christian fiction, or simply have to read it because of the movies (or because everyone else had), don't bother: it doesn't compare to 'Harry Potter' or 'Lord of the Rings'.