How do I know if my lease deal is good or bad?

Compare three things: the selling price (cap cost) against invoice and MSRP, the money factor against the base rate published by the manufacturer's finance arm, and the residual percentage against what the manufacturer has set for that model. If the selling price is near or below invoice, the money factor is at or near the base rate (not marked up), and the residual matches the manufacturer's published number, you have a strong deal. Getting quotes from multiple dealers or a broker is the fastest way to benchmark.