Keynote and PowerPoint run neck and neck when it comes to creating presentations. You can choose themes on the web and then they'll sync down to the mobile version, but again, not very convenient. Basically, you have to pick from Google's pre-made slides and be happy with text-only slides with no image support, unless, of course, you are okay with finishing things up from a web browser. You can add text into existing text boxes but there isn't a way to add, move, or edit them. Slides are technically 'editable' but not functionally. Unfortunately Google Slides doesn't provide as great of an experience as either Keynote or PowerPoint do.