This book was a lot like its predicessor, The Dangerous Days of Daniel X. There's really only so much you can do with one character and his imaginary friends and family, so I shouldn't have been surprised by how similar the two books were.
Despite being much like the first book, it was still good. The short chapters made it easy to read huge chunks in one sitting without realizing how far I'd gotten, but it wasn't a book that was super hard to put down or something I thought about incessantly when I wasn't reading it.
It's been forever since I read the first one, so I can't say too much on the character development between books.
Story wise, I think I liked this one more. The idea of a villain using people for a reality show against their will, and killing them in the end, was fascinating and disturbing (though, probably not very original [I say probably because I can't think of any other books with that theme, but I'm sure they exist somewhere]). I can't remember exactly what made the last villain so bad.
I think that's really all I can say on this one. Usually when reviewing a sequel, I would make some comparisons to the first book, but it's just been too long since I read the first one and since I didn't review it, I don't have anything to help me out.
All in all, a good book. Definitely worth reading if you liked the first one, and I'm really looking forward to the third. :)
I give Daniel X: Watch the Skies three Fists of Rock.