I've worked from home since the late 1990's.  One of the things I really noticed is the ability to concentrate.  I didn't have to shut out other people's conversation, phone calls, etc.  I also didn't have to deal with numerous interruptions.

One big difference since then is that the number of e-mails I received has sky-rocketed.  And IM can also be a problem when you have people that thinks that means you should always be available, even when you're in a meeting that requires your full focus.  (The do-not-disturb button is my friend.) Of course, that's probably a problem as much for in-office workers as for home workers.