I have recently started an IK based campaign and the setting is very interesting and the overall fluff is excellent. You do need a DM who is cognizant of the variance in the setting, especially in regard to mechanika/industrial feel. Two of the new classes are tied to this and would be useless if genric modules are used. Consider, for example, that the use of Steam Enigines has been in place for centuries.If you impart the feel well, the campaign should be tons of fun. The Witchfire Trilogy is topnotch, once you get rid of the railroady stuff in the first module.
Some of the crunch is a bit iffy, points to consider:
The human, racial stat adjustments - a bit uneven.(i house ruled the stats out)
The Ogrun stat adjustments.
Healing rules only stipulate the pain of healing for Divine casters - It has been clarified that arcane casters, including the bard, do not get healing abilities (i created a medic type ability to offset this loss).
Mechanika rules- quite clunky as written in the book. There is a PDF of the IK site which makes it quite simple and once you get the hang of it, it becomes very interesting.
The dead remain dead - no raise dead etc. I love it! but make sure your players understand this - i have my Players have "character trees" ala Dark Sun.
The Monsternomicon is absolutely a must in my opinion; it definitely imparts the right feel to the setting and i have been exclusively using creatures from this.
I would also consider adding the Herbalism and Alchemy? suppliment from Bastion Press as this area is not fully flushed out.
