I've never played a Gust game but unlike Idea Factory, I'm not against the idea of playing one someday. The Eternal Mana games had nice looking sprites, and I heard that despite the series looking incredibly pedo-creepy, and thus keeping me from ever purchasing one, that Ar Tonelico 2 was actually a quality rpg, and the Atelier series has always seemed interesting in that N1 Marl Kingdom-esque way. I own a few Gust games (EM1/2, Roronoa, maybe some PS2 atelier) but I've never gotten around to playing any.
Probably won't get to one since I have rpgs from better devs in my backlog, but you never know. I don't harbor any negative feelings towards the dev though like I do Idea Factory/Compile Heart.