For List API more than one level of lookup expand, allow multi-line text column in lookup expand, allow empty column values in lookup expand
Currently you can only expand one level with look up columns. It would make things a lot better to be able to expand at least 2 levels. (e.g. get Items, expand Comments/Content, Comments/User/Title Also you can't expand columns like yes/no, date, multi-line text etc. and if any of the columns has a null value it will cause an error. These limitations make it very difficult. Constant work arounds required.