I like this product a lot as an alternate take on the Warforged from 3.5. It has a lot of flavor information specific to the Questhaven setting and is partially written in a first-person perspective from a member of the Ironborn, which honestly was less useful to me. However, if you ignore the fluff and focus on the crunch, what you have is a VERY flexible system for creating a variety of constructs, either as variations on a single race or as entirely different creatures. With rules for small, medium and large Ironborn, 20 or so Ability Packages ranging from Acrobat to Divine Mark to Mountain Design for a variety of abilities, and variable ability score modifiers, you can create nearly anything you want with Ironborn. In fact, that may be one failing - if your group is more focused on pure optimization than anything else, a player can probably find a way to make an Ironborn fill any role they like, but playing a living construct will not appeal to every player, so this probably isn't an issue. Some of the Ability Packages such as Secondbuilt even have options within options, allowing for a high degree of customization. In my game, an Ironborn with +2 Dex, +2 Int, -2 Str and the Acrobat Package is doing a great job filling in for a player who always wanted to play a Nimblewright PC.
[5 of 5 Stars!]