Thanks for your interest in TeamPulse. I understand your confusion when dealing with not finished work. It's general problem in every process. My general suggestion is to try to create a smaller stories but you already know that :).
We have a list of reports and one of them is Planned versus Actual Velocity/Capacity with a graphic and a list with not finished/finished work. I'll increase the priority of that report and we will try to add it for the next version.
Till than I can suggest you to move you story to the new iteration and create another story in the old iteration with the done work and link them if you want to track it.
Your feedback is very valuable for us. If you have some suggestions for improvements or missing key features please let me know.
the Telerik team