If you search, there are lots of threads on the various clear hood covers. I think the general consensus is that the low front of the IS gets beat up pretty good by rocks/sand without one of these, and the clear polyurethane covers all work pretty well to keep the hood and bumper looking nice.
There is also lots of detail around cost. There are various options of how much of the front end gets covered, and you can probably find some good references to what is a good price.
Thanks