I think this is a superb action/adventure story with believable, engaging and rounded characters, genuinely threatening bad-guys, and plenty of twists & turns in the plot.
This is the first in a trilogy - with a second follow-on trilogy now in progress. I'm finished the first trilogy and have started the second. All the books in the series are like a box of chocolates - once you've started, it's hard to stay away and you end up forcing yourself to slow down and enjoy it properly !
I won't recap the plot (see Jim Harmer's review for a good summary) but just to say that while this is set in the same universe as the author's "Island in the Sea of Time" series, there is no real interaction or overlap between them, and it doesn't add anything to this book if you've read the other series. IMO this is an excellent first read by this author, if you're new to him.
The intriguing premise is - what if technology stopped working one day ? Basically anything from the industrial revolution onwards just suddenly stops - no electricity, no machines (water, wind and muscle-power still work but that's pretty much it) no nuclear power obviously, no guns, no explosives... It's an interesting idea, and makes you scarily aware of how dependant most of us are on food being produced, and imported, using all those machines.
I think the author does an excellent job of making this "Change" (as the survivors call it) believable - and the new societies that grow up in the aftermath. The results are filled in more with each succeeding book, and I found the developments that he describes to be very plausible. I particularly enjoyed the parts of the second book (The Protector's War) that are set in England.
Yes, the lead characters do get lucky - but then anyone who survives this Change would have to be lucky, as some of the characters point out. Yes, they do adop old-style technology (arms & armour, bows & arrows) quickly - but the book makes it clear they're ahead of the curve in doing so, and plenty of others are just struggling along (or not surviving at all, in most cases...).
Some reviews have a problem with the lead characters being too good at everything. Personally I found them plausible, rounded people that I came to care about over the books. The sort of people you know who are really good at things, and you want to find annoying, but they're so personable that you can't help liking them too. Anyway, if there's a problem with characters who are too good at things, what about Lord of the Rings ? - a trilogy that has plenty of explicit and implicit echoes in this series (I love the character of Astrid as the teenager obsessed with Tolkien, who takes advantage of the Change to bring her Tokien fantasies to life - it doesn't hurt that her pre-Change hobbies included archery, an example of what I mean about the key characters being ahead of the curve in adapting to the Change).
As a slightly-jaded 40-something reader it's been quite a while since I found a series of books that engaged me so much. Highly recommended.