Targetprocess re-invents the workflow board, sort of like combining Trello and full-featured issue trackers and project management systems. The way it lets you create different view to slice the data and drag&drop between grids to change properites of the cards is amazing.
+ Easy to use
+ Incredible customization available
+ Rich, feature-packed filtering query language
What I dislike the most is that the experience isn't consistent - some data types can be created, renamed and tweaked extensively, while some others are set in stone and baked into the system. I would rather have that it was very scaled down, and that you could create your own data types for cards, instead of having a few baked-in types (Epic, Feature, UserStory, Request, Bug etc). And the cards are tied to metadata such as Release, Project, User, Role, Effort etc - these cannot be modified and you cannot use them as you will.
- Cannot rename card types or create more, delete unused types etc
- You have to choose between points or hours as Effort metric - but they don't work the same! Some features are not available when you choose points instead of hours. I'd rather it was only a label choosing "p" instead of "h".
- Multiple stuff like the above - some stuff is build-in and cant be changed and it can be very confusing.
- API is a mess. Everything can be modified in every request, instead of having separate requests for midifying different objects. For instance: you add a comment to a bug, you have to include the user (as an object, not just an id) that authored the comment. However, if you accidentally input the wrong name for the user (but the correct ID), it will actually *change the name* of that user. WTF?
- Query language is very useful, but has some subtle bugs and inconsistencies.