The best was definitely the remove of cell limits and row limits. If I remember correctly, it used to be at 50k linrs , which you reach in no time. The new spreadsheets are way faster indeed!
"All spreadsheet limits mentioned above have been removed in the new version of Google Sheets. The new version of Google Sheets should support 2 million cells of data, though please note that extremely large spreadsheets may have slower performance. Learn more about switching to the new version of Google Sheets."