I worked on something similar. I would recommend a database to capture the information but this could be done completely in InfoPath. My understanding is you would have a formal scored/signed/summary page but then you want a detail view with notes, comments, etc.
I would use a form with multuiple views, capture the details in one view for the supervisor, and then have another summary view that totals scores or summarizes the review or multiple reviews.
I created one that would allow supervisors or employees to add rich text fields with date stamps ad hoc, whenever a good or bad performance event occured, and then these were captured in one location and could be reviewed at the actual review session.
Lots of options you just ned to figure out exactly what you want and the best way to accomplish it.