I've never understood the decision to abolish the long-standing MMO convention of auction houses, but if we must have guild stores then can we at least have them searchable by keyword? It's unnecessarily annoying to wade through numerous pages of crap just to find out whether the item you want is there or not.
I know you can search by category, but they are so broad that they are not really helpful. If you need a specific type of potion or a specific material to level up a crafting skill, only the exact item will do. Especially in large guilds, trying to find the simplest items is a huge hassle.