I've used Office on a Mac for several years now. No problems so far. Yes there have been some implementation issues but both Office 2011 and Office 2016 are beyond the initial teething troubles and perform fine.
Loose Rivets: it's no use telling him to send just the one file. That is not an option in Pages. Actually, the Mac suite of Office programs (Pages, Numbers and Keynote) is a very capable set of programs. It may take a while to get used to them if you have used Office for a long time, but they don't disappoint. They all offer the option to export to an MS Office file, so ask your friend to deliver this file (the link you posted explains this, it is just like the 'save as' option we know from Microsoft).