In most defect trackers there is a comment history associated with a ticket/incident/issue/work item.
I wish to get this same information from TFS via the SDK for a
In order to fetch the comment history you need to access the "History" property on the Work Item revision.
WorkItem.History Property
Obviously the current (latest) version of the work item will have this field as empty, but historical revision comments will be there.
TFS: Getting workitem history from the api
The "History" displayed on a work item in Team Explorer is built by looping through the Revissions and displaying both the fields that were changed and the text in the "History" property