This cozy little archive is a pleasure to research in. It is open in the afternoon, so if you wish to work in both the Diocesan and Provincial archive, you can do the first in the morning and come here after [a late Spanish] lunch.
The research room has three tables with four chairs around each one. Photography is allowed, provided you record the documents you have photographed on a form they provide. The atmosphere is very relaxed, with patrons and archivists chatting together about their research and whatever else comes to mind.
We were looking for notarial records in towns too small to have their own notaries, and the archivists worked one-on-one with us to go through their database looking for any notary that covered the towns. By so doing, we were able to find several books with a wealth of information about these towns. The archivists also gave us the email addresses of two researchers working in the same area that could give us additional resources.
Like the Diocesan Archive at Burgos, the Provincial Archive is small, but the archivists there will bend over backwards to help you be successful.