AVman..
I've used both, and come to let dust collect on a very good dewalt jointer.. The first few cabinets I made with pocket holes I was absolutely amazed. First and foremost, the strength of the joint was/is amazing. Even butt joints.. A flat surface and a clamp is all you need to align up your work.
Peter up there makes a good pint about the material your joining!!!!! I will say though i've done side by side joints with great success. They were only 18"x 10 though mind ya... using 3"w boards..
I heard the norminator comment one time about biscuits "swelling" and creating imperfections on the finish product. Never happened to me,, but something think about.. All in all,,, pocket joints get my vote..and with an ever increasing variety of accessories becoming available...its looking like a good shop investment