Hi @Joe S, good question I should say. If I am in your place, I would prefer Mobile Apps over Mobile SMS for any mobile marketing campaign I get engaged. Why? for this following reasons:
If you get a very attractive and intuitive mobile app which create lots of attention among mobile users, it is deemed to get viral for FREE and help in creating lots of vibe among the targeted audience only for the cost of its development and deployment in Play Store and Apps Store. But, in case of SMS, users to whom you will send the SMS, there is 90% chances of it getting deleted or avoided without any attention.Each SMS will be chargeable in the campaign , not like the app whose downloads and installations are free.
You can get more insights by using mobile app marketing campaign rather than using SMS marketing campaign.
Apps Marketing campaign is far more effective than SMS marketing campaign as apps contain lots of room to make it attractive that SMSs