I also have this feeling that items get more views if they are posted from the app. I have no evidence to back this up. However, the html is much simpler from the app so the items may appear higher in the search ratings.
I'll use the app to list if I only have a couple items to get through. It ends up taking the same amount of time as if I take photos with my digital camera, load them up and type away.
The thing I like most about the app is the ease of adding the best offer option to BIN items. It's quick and there is the option to automatically except offers of a certain amount, or decline offers of a certain amount.
I know you can do this from the eBay website as well, but the only way I can figure out to do it is by revising your listing later, not when you originally list it.
If you know an easier way to do it please comment and let me know! Do you use the mobile app?