I've read all eight Jack Reacher novels. The Enemy is not the best of the books - that would be Persuader - but if you enjoyed the others you'll certainly like this one also. You know exactly what you want from a Jack Reacher book and you always get it, which is more than you can say for many popular crime series. Unlike the rapidly deteriorating John Sandford or James Patterson books, Lee Child knows that readers like Jack Reacher just the way he started out - an alpha male with a sense of fairness, but no time to indulge in tricky deep character development.
The Enemy is a 'prequel' to the other novels - Reacher is still in the army, a young MP and rising star in the elite 110th investigative unit. Being in uniform doesn't seem to cramp his characteristic style that much - he still resists authority and does what he likes in pursuit of justice, helped by the best kind of female sidekick - attractive, talented and emotionally undemanding.
The Enemy does not entirely live up to its promises - the falling of the Berlin Wall adds surprisingly little symbolism or color to the book - it's like, in a far off land some wall is coming down, now lets get back to the story here. The plot seems repetitive in the middle, with a lot of driving here, there, back and back again for Reacher to glean obscure clues that he doesn't deign to share.
We get interesting insights into Reacher's family, although he seems very flat about some quite momentous discoveries & events. But, that's what he's like, and that's what we like. Reading this book right now (May 04), it's impossible not to wish there were a few real life Jack Reachers - decent guys with a conscience, but tough as guts - to fix matters up in Iraq...