This is potent stuff, and it has the same big catch that creating lasting change does: duration. Making something permanent from nothing is impossible; the magic maintaining the thing will naturallydecay as time passes, and dawn and dusk are important thresholds in the day that sap the strength of ongoing magical effects. Eventually, unless the caster spends time, effort, and energy to refresh the magic frequently, the spell will wear off and the conjured thing will go away. So, the armour vanishes, the sated guest becomes suddenly hungry again, the pile of gold melts away, and so on.
But if you really need a rope for a few minutes, or a plank across a chasm for thirty seconds, or an impressive mansion for the evening, this can do it for you.