I had whipple surgery 12/2009 and while the recovery was not a picnic, it was not anywhere near horrible. Everyone is different, so I cannot predict how your father will recover. My surgery was 6.5 hours long but I was only in the hospital for 6 days which is a record for my surgeon. The hospital stay varies for everyone and in my humble opinion is dependent on the physical health of the person before surgery. I was just shy of my 54th birthday and in pretty good physical health (no heart disease, no diabetes, average weight, exercised regularly).
Before my surgery I was concerned that I would never be the same person. I can tell you that while I have some issues my stomach occasionally, I am very much the same person and do the same things. I still run and exercise, eat right, I went back to work 6 weeks after my surgery to my (admittedly sedentary) desk job.
Tell your dad that mostly only people with horror stories post on websites about their experiences, so to take of it with a grain of salt.
I will not minimize the seriousness of this surgery, but it's the only potential cure for this cancer, I fell blessed to have been able to have it, and I would do it again in a second.
Please feel free to email me (email@example.com) if you would like any specific information about the whipple.
Survivor of breast cancer (1994), thyroid cancer (1999), cholangiocarcinoma (2009).
My comments, suggestions, and opinions are based only on my personal experience as a cancer survivor. Please consult a physician for professional guidance.