Let's see...Ironhand is the sequel to Stoneheart. It was a lot more intense and darker than first book. In this edition, our three main characters, the Gunner, George and Edie all get separated and most of the book is spent jumping from one character's story to another's. Usually though this isn't confusing since the author makes it clear who's talking each time. It is frustrating though when the chapter ends with one character in some sort of peril and you have to wait 3 to 4 more chapters to find out what happens! That's a good kind of frustrating though - means you're interested.
The final book in this trilogy come out in April and is called Silvertongue.