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!
New limits are here:
https://support.google.com/drive/answer/37603?hl=en
Number of cells: 400,000 total cells across all sheets - this is the one i don't like. If you log substantial amount of columns, it fills up pretty quickly
Number of columns: 256 columns per sheet
Number of formulas: 40,000 cells containing formulas across all sheets
Number of tabs: 200 sheets per workbook
GoogleFinance formulas: 1,000 GoogleFinance formulas
"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."