Sure, we mention it even in the README (https://github.com/cowbell/sharedrop/blob/master/README.md). There's probably a workaround if you have a phone with internet access - you could create a local WiFi network on it and connect to ShareDrop through it. Haven't tried it though.
And one advantage to this is that it anything that can view a web page can reach it. I don't have to ask my grandma to install an app on her phone to get a picture on her desktop computer from me : )