This is not at all ready to replace Word. I have to read and edit (often quite heavily...sigh) dozens of student papers at a time and Word is superb at making that process fast and smooth. Writely would have me pulling out my hair in no time because it is far too sluggish (not to mention simply not as good at editing and commenting).

It is probably great for people who don't do much word processing but until it gets significantly faster it is simply not a good substitute for the desktop version of Word.

oh.. as an aside, Open Office also falls far short of Word in the editing/commenting department. This sucks but it is the only thing keeping me from being able to switch to, say, Linux.