This took me completely by surprise - it wasn't a review I solicited at all, and the module has been out for quite a while. Although readers should hit the link above to see the whole review, I'll quote my favorite part:
I found this to be one of the strongest adventures that's been published by the OSR. A few of my favorites (that haven't been reviewed here yet) include Stonehell, Castle of the Mad Archmage, and Death Frost Doom; The Spire of Iron and Crystal is right up there in terms of creativity and scope and is a must-have.
Maybe I'll write up some of the stories about this module at some point, if I can manage to tell them well, because some of the things that have happened in the module (especially at the session run at the first NTRPGCon) were freaking hilarious.
The module's available in two places right at the moment, because it's awaiting an upgrade to its maps and art before coming out through Frog God Games. You can get the pdf at lulu or a softcover of the original at Frog God Games. I haven't loaded it onto RPGnow, at least not so far.