IMHO, its too bad, since I would of really loved to have seen Dropbox more tightly integrated into iOS. (iCloud will be and it might be my replacement for Dropbox). Though for sharing, I don't think iCloud will have those features for a while.
As a user of Windows, Linux and Android all I can say is "thank fucking god". It would have destroyed a perfectly good cross-platform product.
As a user of OS X and an iPhone, I had the same reaction. One nice thing about Dropbox is that it just works with all my Windows-using friends. It just works through a browser interface. I obviously like some Apple products enough to use them, but I too would hate to see Dropbox acquired by the company. I don't think it would be as bad as Cisco's acquisition of Flip (http://jseliger.com/2011/05/08/will-we-ever-find-out-what-ha...), but I can't imagine such a thing turning out well for Dropbox or for users.