I have owned a hard-back copy of this book (4th edition) since 1964, when I was still a student. At that time there were not many books on number theory available, and as far as I remember, Hardy-Wright used to be recommended as the best book in the field. I had always regretted the absence of an index, which made it very difficult to use the book.
I have been aware of more recent editions of the book, and finally decided to purchase the latest edition a few days ago. What an improvement! Even though the old style notation and terminology has been preserved, the notes have been updated to include more recent results, and a a new chapter on elliptic curves has been added. An index is now in place, but it could be more detailed.
One must not forget that the book is directed to students of mathematics and practising mathematicians. Comments made about the book by other people should be read with care.