Another minor issue is when opening a spreadsheet when one is already running. When you do this, Excel opens the sheet within the currently running spreadsheet, and puts the one you are working on at the background. To access the original one, you need to minimize the newly opened one and maximize the old one. This prevents you from using alt-tab to switch between spreadsheets. A workarounf would be to run a second instance of Excel and open the new spreadsheed there. You will get an error though regarding "personal.xls" being already opened. Everythime Excel starts, it accesses personal.xls, and since one instance is already running, its being locked. Just click on "cancel" and everything should work.
To compare, Excel in Windows would open a new (sub)instance of Excel in another windows with the new file.