Rowing Machines - What do you think about them?

Anyone use a rowing machine or know much about them?
I'm about to pull the trigger soon on a LifeCore R100 rowing machine,
the best one out there ($1300). I read that they exercise your whole
body and burn calories a lot faster than exercises that only use your
legs. Plus they build muscle strength. I was thinking of getting a
weight bench or a home gym, but the rowing machine sounds far better
for weight loss. Would you agree? I have been walking for 4 miles a
few times a week, but I can't walk too much more than that, because my
knees will get sore if I do. That's what happened a few years ago and
it took 5 weeks to recover. I want to burn more calories and more fat
every day, so I wanted to find something else I could do for exercise.
My weight loss seems to have slowed down too much lately. I need to
kick it up a couple of notches. From what I read, rowing machines do
everything I want all in one machine: cardio, weight loss, and muscle
building for the whole body. Oh yeah, they are easy on the joints too,
so my knees will be spared any injury no matter how much I use the
machine.