I use PicturestoExe for presentations although designed to produce an exe presentation so you need nothing pre-loaded onto the computer used to give the presentation I often save as a video as some places their virus software does not like exe files.
Speech music video and stills can all be used, with zoom in and out on the stills. After using it I would not return to power point. Only advantage is being able to print pages, but why would you want to?
As to Visio depends what you want to do, there are many better packages but each seems to specialise in one direction, Visio is Jack of all and master of non, and if you don't want loads of programs loaded onto the PC then it is a good all round for the odd use.
It is surprising what you can do with the MS VB for applications built into to the Office Suite. The main problem is schools and collages seem only to teach microsoft products, they must get a back hander! Also same with art seems only option is Photoshop. So give a school leaver PowerPoint and they know what to do, but give them Picturerstoexe and they scratch their heads, it is very similar to flash not seen flash for years, seems apple did not like it and did all they could to stop it being used on their computers.
Today I use a lot of Java Script for web based presentations however I manually write it which is time consuming not something one could do on a commercial basis, you can get tools to auto write Java Script for you, but I don't want to pay so I do it manually.