Similar to this, I think that the whole experience of jumping between the backlog and the sprint in general is a little slow because it isn't necessarily easy to find what you're after in the backlog. Today we were in a sprint planning meeting and continually had to refer back to the backlog and search for the particular story we were trying to either modify or simply get more detail on (since it gets truncated in the sprint view).

That being said, this is our first week using the tool so I wouldn't be surprised if there's a better way to do what I was just describing.