Got my copy in November, read it twice, lent it to two friends, and the spine already has that faint white line that says 'I've been opened a bit too enthusiastically.' Not a full crack yet, but it's on its way. The cover material seems fine, no peeling or anything, but the binding is where it's at. For a nearly 900-page doorstopper, the glue just isn't up to the task of frequent, flat-open reading.
I compared it to my older, equally massive 'The Priory of the Orange Tree' paperback which has held up better despite similar use. The paper quality in 'Iron Flame' feels thinner too, which probably stresses the binding more when you're wrestling to keep it open. It'll survive a read or two, but if this is a book you plan to revisit often, the durability is a genuine concern.