PVC is affordable, and comparitively easy to install, however it may be more susceptible to damage during maintanence or installation. PVC is sensitive to UV degradation, and will become brittle if left out in the sun.
PVC is particularly vulnerable to UV degradation, and needs at least 12" of dirt or sediment as coverage. However, for their low price, and ease to install, PVC is still a highly popular choice for backyard pond projects.