The Excel functionality is much better in Beta 8, but I have noticed a few small annoyances.
1. I still have an intermittent problem where one of the excel windows on my secondary monitor will go to the primary monitor when reduced to the taskbar. Then I have an excel button on both taskbars. When I select the button on the primary it will maximize back to the secondary monitor. This is not consistent so I don't know how to recreate it. It mainly happen when I have more than 4 spreadsheets open.
2. The preview thumbnail that pops up when I hover over an excel button on the secondary monitor shows the same thumbnail for all excel buttons. The file name is correct.