I purchased this car rather cheaply from an estate and the brakes went out during the trip home - the rubber hoses had deteriorated. I had the system inspected and overhauled at a local RR dealership for around $2000USD. The exhaust system is original and rusted, so I'm planning to replace that with a stainless steel version. The suspension components are very worn (springs, shock absorbers, etc).
My car is one of the earliest examples, from the first model year of the Silver Shadow. As everyone notes, the car is comfortable, elegant, and powerful - exactly as you would imagine a Rolls-Royce would be. Though people complain about the "remote" steering, I love the ease of driving the car. After a hard day at work, climbing into the Rolls gives me the feeling I'm already home, before I've even left the parking lot. I plan to keep the car a long time, and can't imagine a time I'll be too old to drive it. I'll admit that the handling is too vague and wallowing for my taste (I still have the Porsche, and my previous cars were sports cars), and when I replace my shocks and springs I'm going to stiffer examples used for later models than mine.
So far, the car has proved fairly easy to work on and maintenance has been reasonable for a car nearly my age. I've gradually worked through the various systems of the car and made replacements and updates where necessary, which has helped. After the suspension work, my final project will be converting the AC to r134a.
I would recommend that someone interested in a Shadow look at the Silver Spirit/Spur cars first - they have more understated styling, but mechanically they are much improved in a lot of areas, and prices are similar. Get a Shadow only if you specifically want a Shadow, and not simply to own a Rolls-Royce.
I tried to convert to a R134 system on my 1969 Silver Shadow and it didn't work. Changed everything, but the controls on the dash. Eventually I changed it all back. It hard as heck to find R12... but it at least it works.