Old Man's War is a great read. The whole series is pretty good, in fact. For that matter, the whole series is excellent, and worth reading for anyone who likes a good science fiction adventure story. Agent to the Stars is written by the same guy who wrote Old Man's War (as you can see from the cover blurb over there), so despite this being the author's first book (which was really written as a proof-of-concept for himself), I expected a lot out of it.
The book doesn't disappoint. It's about Tom Stein, a young agent in Hollywood who's given the task of representing an alien race that wants to present itself to the world. The reason they want an agent is because they're gelatinous, and small like farts. They need someone to make them look good, and Tom Stein is the person they want to do it.
The story is a breezy read, and it's a lot of fun. The premise isn't one to be taken too seriously, but Scalzi still treats the story that way. It reminded me a little bit of A. Lee Martinez' works, where you have funny characters and silly situations, but the stakes are still real. Scalzi has a natural style with his narrative, and he creates good main characters. There are some secondary characters who are a bit one-dimensional (the standard Hollywood characters are all a little stereotypical, but they work), but otherwise he creates characters who feel real, and are easy to root for. The book probably isn't as thought-provoking as Old Man's War and its sequels, and it may even be predictable (I, at least, figured out how the book was going to end about 150 pages before the end), but that's not to say that I didn't enjoy it. I enjoyed the hell out of it, in fact.
This was the first non-Old Man's War book I've read by Scalzi, and I'm glad to say that it was just as entertaining as his other books. This one isn't quite as serious as that series, but anyone who's read those books will find a recognizable style. I'd recommend this book to anyone, really. The book is still free to read online, too, so you really have no excuse not to read it.