I’m really not too sure what to make of this one. Overall I think the three “I” series adventures went progressively downhill with each installment. The main problem here is that this isn’t even really an adventure module in the usual sense, it’s a mass battle scenario. Perhaps it was a ploy to encourage players to take notice of the mass battle rules “Fields of Battle”, although you don’t need these to use this scenario, a simple rule system is included. That however, is part of the problem. In a 24 page PDF, only about half of it is really the “adventure” itself, the rest being advice on running it and the rules and stats for it. The real “meat” of the material is a little thin on the ground.
I’m not sure that the goblin leaders motivation for starting a full scale war against the local region (ie: the PCs attack on the small stronghold in I2) are entirely convincing, but such things are probably best decided by the CK on the basis of what best fits your campaign setting anyway.
Despite liking the previous two in the series, I have to say unfortunately, that I probably wouldn’t have bought this one if I’d read it first. Whether you’ll feel the same way depends entirely on whether you want to include a mass battle against some goblins, etc, in your campaign at 2nd-3rd level.