As far as I remember it had basically the same issues as Invision or Zeplin, like layers suddenly not selectable anymore, layers' bounding boxes moved around the canvas, Symbols not being correctly displayed/expanded, etc.

A big advantage is, that you can create nested folders - something, that could come in very handy in bigger projects. Invision's sections are not up to the task.

I guess, ditching Invision for Gallery won't result in much greater satisfaction. On the other hand, you save quite some money.