I haven't tried this, but I'm certainly willing to assume it works as advertised. But for many users, the best way to distribute Powerpoint presentations to people who don't have Powerpoint won't cost US$49... at least not when Microsoft distributes a free Powerpoint viewer:

http://www.microsoft.com/downloads/details.aspx?FamilyId=428D5727-43AB-4F24-90B7-A94784AF71A4&displaylang=en

or when recent versions of Powerpoint can export packages that can be viewed without Powerpoint installed.