I like how easy it was when creating my first app, everything went smoothly! The support team are very helpful as well with any questions or doubts that you may have about their product/service they will always help out at all times!! Nothing really i dislike but if there's anything then maybe add more features? They could expand some things such adding new design elements etc..
But other than this nothing much else comes into mind so far :) Great start up business who do great quality apps which has helped me create many different types of Apps using both iOS & Android platforms :).