I love Google Presentation. It is simple to use and creates great embeddable presentations like this one:
One of my most favorite features of Google Presentation is the ability to add YouTube videos. Google makes it so simple! (You can see a video added to Slide 4 of the above presentation.) If you have ever tried to add a video of any kind to PowerPoint, you will appreciate how easy it is to add a video in Google Presentations.
I also love the ability to collaborate with others on a Presentation. No more emailing attachments and files back and forth. Simply share the Presentation and voila! Having students do a group presentation would be easy with Google Presentations.
I hate all of the flying animations and whirlygig transitions in PowerPoint. I love how simple the effects are in Google Presentations. And I love it even more if you don't have to use them!