For a New/non-loaner RR Sport HSE: 10% off MSRP and $14xx/mo is a great deal.
If you gave me a $1500/mo lease budget, I would lease 2-3 cars and not be driving a RR. But I get it: if you want the only check-engine-light Queen Elizabeth will drive herself, that goes up a mountain sideways, and money is no object — it’s the car not the deal, so make the best deal you can.