Prime Obsession or Millennium problems?

[2sin54]

Hello, people. So I am considering getting a book on mathematics (of the "popular book"-ish realm). However, I do not want it to be too much aimed towards the general public (something like Kaku or Hawking would write in Physics). I want to buy one of these two and I am asking for guidance which one is more worthy of getting (if you have read both):

1) The Millennium Problems: The Seven Greatest Unsolved Mathematical Puzzles of Our Time by Keith J. Devlin

2) Prime Obsession by John Derbyshire

 

[jbunniii]

I haven't read the first one, but Prime Obsession was surprisingly good considering the author's day job is writing conservative political opinions. It is definitely not aimed at the general public - you need to know calculus and a bit of complex analysis to make any sense of the mathematical chapters. (As I recall, his chapters alternated between history/biography and math.) It's not a fully rigorous treatment, and the author glosses over some important details, but it's a nice overview. My only complaint was the typesetting. I think the author used Microsoft Word instead of Latex, and it shows.