I”ve just discovered quite a lot on the condition of the Exchequer Pipe Rolls as sources for historians nowadays. Here are some useful links for researchers:
The Pipe Rolls Society, in charge of editing the manuscripts, has published more than 90 volumes of edited material that is available for sale throught their website. This is good news for scholars. However, the same Society is announcing the digitised volumes of their editing work which may be found here but only covering the reigns of Henry II, Richard I and John. (1154-1216).
For the other medieval pipe rolls, the manuscripts covering the period 1225-1312 have been digitised but not yet edited. Scans are available here by courtesy of the University of Houston.
However, one should get familiar with paleography and the editing conventions as the text is quite impermeable to the modern reader. Furthermore, special knowledge of medieval economics is required in order to make sense of the financial information that the Rolls enclose.