I've also found the official conference app unusable. It takes about a minute to start, which is far too long when you're looking for the location of a fringe event, for example. These things need to start instantly. The "killer" feature of the app is, or would be, the ability to create a personal agenda. In theory, you can do this: adding debates, fringe events, and training events. In practice, nothing that I "add" to my agenda actually gets added.
It would work quite nicely, even with the delay, if "adding" an event would just create an entry in my calendar app. Actually, that would be better than creating another diary in the official app. But that doesn't appear to have been considered.