I've had a C2 (Model D with PM3) for a number of years. I really like the ability to rerow a previous workout, basically race against yourself. I have workouts going back to 2007 so I can see how I compare to the younger me.
I pretty much stick to the 5000 meter rows, not sure I'd enjoy much more than 20 minutes on the thing. I am now combining my C2 workouts with SimpleFit and it's starting to yeild some good results. I also run and cycle so for me it's just an option for sprint type workouts. Like a PP stated, anything of a longer duration I prefer to do outdoors on something that moves (feet, bike, etc)
The question is, are you going to die sitting on the sofa - or doing something interesting?