It's for MS2s. Each set of gross and histological images is organized by system, and will tutor you on the common pathologies. I'm using it to prep me for recognizing path images on the boards. I'm pairing it with FA and Goljan, using a systems approach. e.g. I study CV in FA, Goljan, then WebPath in the same sitting.
By the way, there's another version with more images, questions, and tutorials, and can be found here.