AppCode is in Beta - it's going to be slow and its going to crash. Even though you have stated that "tools don't have to be pretty to be functional" I think you have contradicted your point here by writing off AppCode on that basis entirely.
As a software developer, fair criticism of a tool should never rely on its aesthetics but rather on its ability to solve problems and solve them productivity. Eclipse, Emacs, Hudson, et al are tools I wouldn't say are aesthetically pleasing but they are very successful at solving the problems they were designed to solve. Thus I believe aesthetics should logically be placed secondary to utility.