As I'm sure you know of the global sucess of Harry Potter you are probably all aware of the mature storyline that it develops into in the last 4 or so books. Bearing this in mind it is safe to say that 'the Philosophers Stone' is simply used as an introduction to the magical realm and, of course, the characters.
In this book we are introduced to Harry Potter and boy who has not yet discovered his magical potential and soon finds himself swept up in a torrent of magic and witchcraft - transforming his old, bad quality of life into one of endless possibilites. He is somewhat of a legend within the wizarding community due to his encounter with the dark lord in his earlier life.
Without giving too much of the book away it follows him through his adventures of the first year at Hogwarts.

The book really does not appear to be going anywhere as the stroyline has little or no relevance to the later plotlines. That is not to say that it is a bad book. The plot is clever and the book is well written and can be enjoyed by adults just as much as kids. Just bear in mind that you will not be wowed until the later books where the larger plotline unfolds.
To conclude I would recommend reading this book as it is a good read and certainly will keep you entertained for the duration of the time you read it.