The only time I've fired up MS Word in the last few months is when I need a word processor that's a little more processor efficient and won't cause stuttering on a video being played on a separate monitor.
I know, I know, using a Microsoft product for system resource efficency seems backwards, but like +Anthony Ridley
said, Docs can get a little laggy when you get more than a few pages in. At least, it does on my little netbook with 2 gigs of ram.
Other than that, since the introduction of #googledrive integration with Windows, I've found less and less need to use desktop software. If full offline functionality could be guaranteed, then a #chromebook might just be worth the £400 they charge for it here in the UK.