I had a total hip replacement about eight years ago and a total knee replacement two years ago.
Looking back on it, neither one was that big of a deal even though I had to stay in the hospital for a few days longer than normal to make sure my bladder and bowels were working properly after the anesthesia.
The recovery and conditioning was more involved, and more painful, for the knee than it was for the hip. But you have to stick with it to get back full function. If I wanted a stiff knee joint I could have gotten a wooden leg (and a parrot), but Medicare wouldn't pay for that, so I got the high tech knee joint.
Be sure to have your doctor prescribe the machine. I forget what it's called, but you strap your leg into it for several hours a day and it exercises the joint. The medical supply guy brings it to your house and sets it up and comes and gets it when your done with it.
And be sure to follow the Physical Therapy program. You have to stretch and strengthen everything or you will end up with a stiff leg.
The bottom line is that after about ten years of being crippled and able to get around only with a walker, or a cane on a good day, I can walk pain free with no support device.