I always rate as is. where you talk about the course you can mention potential and circumstances. I reviewed Paul B Johnson after Hurricane katrina and it had some issues due to damage. I rated it as is but noted the difficulties it was having. when everything is back to normal you can update your review.
Here's a related question: is it ethical to update your rating/review based on secondhand info. Take the circumstance above: if the course rating was given based on hurricane damage, and it becomes obvious from later reviews that the course is cleaned up and back in pristine shape, is it okay for magictenor to upgrade his rating based on the added info and add a footnote to his review explaining what he did?
(For the record, I'd say yes, it's okay to change ratings without replaying based on new info. For instance, if I played a course and had docked them 1.0 points for no teepads and crappy baskets, and I saw that they'd added "5x10' concrete pads and Mach Vs throughout," then I'd have no problem changing my review score and adding a footnote. Other thoughts?