They are really useful materials, as noted in the article and in above comments it's possible to take advantage of the inherent 'directionality' of the material (anisotropy) to provide mechanical properties of a required value in a given orientation. Generally, this is to do with tensile strength as it's relatively high cost means it's currently used only where strength/weight is important, but it would be possible to 'tune' it to modify vibrational responses and other characteristics - I'd have thought you could design a 'deformation path' in a similar manner.
A real problem in carbon fibre structures is damage accumulation - repeated relatively minor impacts can cause delamination and other undesirable effects which can lead to catastrophic failure with very little warning (although some composites are better in this regard than others). As such, they have some distinct failure modes that no-one can model quite as well as they can for the metallic counterparts (its anisotrphy inherently complicates analysis, amongst other factors), hence carbon fibre parts in safety-critical areas tend to be over-engineered as designers aren't quite sure what they can get away with. It also means that they're not best suited to applications where they might suffer repeated low-scale impact, such as domestic vehicles. Aerospace/F1 are acutely aware of the issues and can deal with them through controlled maintenance and lifing, not sure that'd hold for a common-or-garden car chassis. I gather certain developments such as inter-layer weaving can mitigate some of these problems, but I'm not sure how useful or practical that currently is.
As I think of it, another problem might be the stiffness - composites aren't very good under strain (essentially they don't really like being stretched) and most car chassis have some compliance in them to increase passenger comfort - not sure if this would lead to gradual loss of integrity or unacceptable compromise. No idea if it (comfort) would be an issue, but some thought might have to be given to it - as is perhaps obvious, it's not such an issue in an F1 car.
