Thats a great question:) Smartmockups is a result of our personal frustration. When you need to send a design to a client or to put together a quick presentation, you don’t want to go through hundreds of mockups and to deal with a lots of features. Also Placeit can became quite expensive.
With Smartmockups we want to put quality of mockups over their quantity and make the process seamless and fast. It will remain free and we plan some other revenue streams (to cover the costs) like bundles or Mac app with some advanced features etc.
The main advantage is probably the price. Placeit is really expensive and I'm not sure if it's bearable for all freelance designers. Another may be the speed, processing in your browser and connection with already made mockups - that means we support the original authors
With Smartmockups we want to put quality of mockups over their quantity and make the process seamless and fast. It will remain free and we plan some other revenue streams (to cover the costs) like bundles or Mac app with some advanced features etc.