They frequently update the material and their software. The program on your PDA stops working when the subscription expires, apparently. That is a disadvantage. If you don't mind a monochrome display, the product is excellent--especially the integration of dosage calculators and such. They abbreviate a lot of terms. And it is fast. :) No bells and whistles. Not much graphical information. If you want to deal with the authors only one time, you may want to consider other software. PEPID is more like a service contract.