Yes, repairing a Sub-Zero refrigerator is almost always worth it. Sub-Zero fridges are built to last about 20 years. A new built-in model often costs $8,000 or more, so even a big repair like a new compressor usually costs much less.
Replacing a built-in fridge is also harder than most people expect. A new one may not fit the same opening or match your custom panels.
Replacing your Sub-Zero makes more sense if the frame is rusted, the doors are warped and no longer seal, or parts for your model are hard to find.