Although it seems like an absolute necessity, there just doesn't seem to be an end all front end submission solution for WordPress. This plugin, without question, comes the closest though. While, the only viable competitor, Gravity forms is a lot cleaner and well maintained it lacks the essential frontend user interface and editing capability that makes WPUF so awesome (Plus you have to pay for it, ugh). As much time as I have spent working on this and after reading just about every post in the support forum, I figure I might as well share my thoughts. I would certainly be willing to contribute if there were any indication that the following additions could be made to the plugin.
support for multiple forms - This is pretty self explanatory. In my case, we need multiple forms for different custom post types. A fork of the plugin by another developer sort of works but it overrides the custom fields portion of the plugin which obviously prevents it from being a final solution. I'm not having much luck doing it differently.
Recognition of WP capabilities - For instance, users should not be able to edit or delete posts that have been published if they have not been granted the edit_published_posts capability. I was able to take care of my issue by modifying two lines of code so it seems like it wouldn't be too difficult to implement a more solid fix. I use the User Role Editor plugin and it has allowed me to make some useful changes to what users can and can't do.
Slightly less Major Stuff
Support for custom taxonomies - This is kind of a big one for me. I used Tareqs guide for extending the plugin to add some check-boxes for custom taxonomies and it was not difficult but dashboard support for this would be cool.
Support for custom post types - Like taxonomies, custom post types are becoming utilized more and more. It would be nice to be able to create multiple forms and indicate which kind of post type they would be.
Support for check-boxes for custom fields - It seems strange that there would be text options for custom fields but not check-boxes. Again, I was able to use the guide to hook some check-boxes in so not really an issue but I'm sure people would like to see that in the back-end.
Also, just a bug
When the rich text editor is enabled, and the images are inserted in to the post with the add media button, images become associated with both the post and the add-post page. So, all of the images appear below the add post form for all users. I'm looking in to fixing this.
Big thanks to Tareq and everyone else who has worked on this plugin. WPUF is the hero that WP needs.