Yes, GCSE is its level for a brief overview into the entire book but you can re-read it and analyse it a much higher level. I've read it twice whilst at University and keep discovering new things in it which in turn gives me a greater insight into the vast number of themes both in the book and in life.
It's a fascinating and unique read. Quite concise too - you don't need to study it, just put it beside your toilet and dip in as and when (I await the criticism about it only being fit for toilet paper!)