In leases you're always upside down until you're about half way through the lease, depending on the car of course. Some cars like Range Rovers, Saabs, etc. you will always be upside down because the value of the car drops so drastically.
I, for one lease all my cars for 3 years and sell them a 1.5 to 2 years into the lease. By that time I am up on the lease and can walk away with a couple of grand. This works out good for me since I usually go over the 12k a year.
Example: I leased an Audi S4 for 36 months and sold it in about 20 months. The guys paid off Audi and gave me the rest in cash. Made $2k on it.
I leased a 02 BMW E46 M3 and kept it about 19 months and had a hard time selling it, but finally sold it but with no extra cash.
So, you taking over the lease is an easy way for you to jump into the car, especially since the guy didn't even drive it that much. At the end of the lease you could turn around and sell the car and probably make some money on it, unless of course you decide to keep it.