I've been using PowerApps for about a year now, and I have found that the application has a solid foundation but there are still more features that I am looking for, here is a short list:
1. Ability to use a Sharepoint Document Library as a data source
2. Control to attach a document to a form
3. Labels - Radius options just like buttons
4. Gradient options for Screens, Labels, Buttons, Icons
5. Shadow options for Labels, Buttons, Icons
6. Ability to rotate Labels, Buttons, Images and Icons
7. Ability to submit multiple forms on the same screen
8. Support for link tags (<a>) in the html text box
9. More HTML support in HTML text box (RGBA colors)
10. Minor animations for Labels, Buttons, Images, Icons like Slide and Fade
Bensack on: ALM for PowerApps DataFlows