Thanks for the feedback, Tim.
Let me add some more information on this topic: First of all, it is NOT a requirement to have a photo for every entry, BUT the entries in the app will look better with a photo.
If an entry has a photo, we use a small thumbnail in the section overview screens of the app. See the screenshot for "Shows what's near you" on this page as an example: http://www.guidegecko.com/iphone-travel-apps
This screen shows all entries (articles and listings) of the section in a list format. If the entry does not have a photo, we use a placeholder instead. We currently use an unobtrusive, gray, triangle shaped icon as the placeholder, which shall make it look natural and avoid the look and feel of "there is something missing". It works pretty well for this purpose. Of course, if some entries have a photo and others don't, users may still feel that there is something missing for these entries.
In a nutshell: it is better if you have a photo for every entry, but we can publish the app also if you don't.
Hope that helps!