Daniel is an alien hunter whose family was killed, and his parents left behind for him 'The List' of aliens on planet earth that must be eradicated. The books follow his adventures in pursuing them and taking them out, while mixing in everyday boy dilemmas about friends, girls and life in general. Daniel X has powers that allow him to conjure people and things, which helps him defeat the aliens along the way.
As the list gets shorter, the higher-ranked aliens are harder and harder to kill, which means he's at more risk of getting killed himself. The aliens methods are creative, and the character names (the nasty landlord is Mr. Gout) will make the adults that read it have a little giggle.
One thing I like about this series so far is that the chapters are really short, so if a parent wanted to find a chapter book to read to a child that was maybe 10+ years old, they'd be able to read a couple of chapters a night. As with most books you're going to read aloud to your child, I'd recommend reading it first to see if they're up for the gore factor, but overall, it's aimed at this age group so I'd feel comfortable reading it to my kids at that age.
While it's definitely a simplistic adult read, I appreciate that it's not too juvenile in that Patterson still uses words that they'd have to occasionally look up and has some complex sentences so that the kids reading the books would be challenged and also empowered to keep reading higher and higher level books.
"Daniel" also maintains a blog, if your kids just keep wanting more...right now, he's promoting the sci-fi thriller District 9.
I have a 12 year-old nephew who will be getting both Daniel X books, and I'm sure he'll love them; Good Morning America recently rated it America's best book for boys!
*I received a copy of Daniel X: Watch the Skies from Mother-Talk in order that I could review it.