The free online versions of Word and Excel don't have all the features of the paid version, but they're steadily coming closer. The latest batch of updates includes improved comment support in Word and the ability to correctly open spreadsheets which include VBA code in Excel.
Note that the web version of Excel still can't execute VBA code -- you need the full suite for that -- but, as the Microsoft announcement post notes, "we have now added support for editing files that contain VBA without removing (or corrupting) the VBA contained in the file".
Other improvements include simpler header and footer editing in Word and the ability to odd Office Online apps to the Chrome app launcher. See the announcement post for the full list of features.
More Office Online: Commenting, printing, Tell Me, and more [Office Blogs]