I used Improv on the original NeXT computer and I thought it was wonderful. I think it was perfect for what spreadsheets are supposed to be, but not for what they actually are. Spreadsheets are generally very sloppy, an according to a study by Microsoft, more often than not, don't actually perform any calculations. They're primarily used just to make semi-structured lists.

Show some people the Insert Table and they'll think you're some sort of magician. Then they'll ask why everything has to be so tightly organized around rows and columns.