Endurance is a decent feat if you've got a DM who actually uses natural hazards. Although in campaigns not perpetually stuck at low levels I imagine it gets less useful over time.
Iron Will is an odd prerequisite feat because of how many different classes it allows you to qualify for. It would almost justify it as a decent feat even if it didn't do anything, so throw on +10% resistance to save-or-lose and it not actually that bad.