This book is still universally agreed to be the most formidable, longstanding and most important academic proposal and defence of the view that all the main world religions are best understood as roads to God i.e. as vehicles to aid humans to reorient their lives from their natural self-centredness toward an increasing centredness in God/The Divine/ultimate reality. No one can seriously challenge that proposal (called religious pluralism) without facing up to what this man has said on the subject more than anyone else.
Evangelical Christians (and I was a well read one) are endlessly rejecting any mention of his ideas but very few have ever actually read anything much at all of his writings. The few academics that have, tend in my experience, to have mis-understood certain key basic ideas on which the whole proposal stands, probably due to their overriding dedication to their existing Christian beliefs. Thus they create straw caricatures of this great academics important work, and kick them down as if it were easy, doing themselves and any discussion of world religions only harm. The man widely regarded as the leading Evangelical Christian apologist in England Dr Alister McGrath recently took on Hick in written debate. He showed great academic discourtesy when by chance he revealed how clearly he'd read virtually nothing of Hick; and most importantly how he'd neglected to read this book which is widely regarded as his most important and truly erudite work, and so McGrath looked rather silly as a result, despite trying to look clever and impressive attacking ideas he clearly felt he already understood but showing his own academic ignorance. (See 'Four Views on Salvation in A Pluralistic World' ed. Okholm - if you're a Christian you may enjoy that book much more as you get 3 other Christian rooted views in debate with Prof. Hick with each person responding to the others etc).
Anyway, for those reading this of greater emotional security, religious maturity, and who desire full academic rigour it's worth mentioning that this edition updates the book to take account of over a decade of academic consideration and attempted criticism. It shows just how strong the remarkably simple theory remains despite desperate attempts by so many of the religiously insecure to pull it down given how it so challenges our traditional and limited human views of God and the Universe and the whole value of beliefs vs actual human transformation from self-centredness to a reorienting in the Ultimate Reality. Briefly put, the book shows how it's the transformational power of a religion to move people out of primitive selfishness and toward deeper reorientation in the divine, which is ultimately our best and only measure of its truth - given that we can't ever be 100% sure a) whether god/the divine is definitely there or not, and b) what religious ideas are accurate about that divine reality (is it personal/not, or beyond such a distinction etc). Christians immediately talk of the uniqueness of Jesus etc (as I used to do) but he's dealt with that issue in depth elsewhere (see his The Metaphor of God Incarnate 2nd edition). The deepest point being that no 'God' worthy of our attention would have ordained a human journey where what you believe is the chief criterion for your being 'ok'. It's a radical yet not so radical and liberating proposal - and feels intuitively true largely because it explains the utter haphazardness of human religious beliefs over all human times.
I cannot commend it highly enough - an easier to read form of it is in his other book called The Rainbow of Faiths which is a less in-depth but more accessible startpoint for many before climbing this great philosophical summit.