ADVANTAGES OF LEASING:
1) You always have a new car under warranty.
2) You can have a more expensive car for the same monthly payment as a purchase.
3) You will probably never has to spend money on anything other than oil changes.
DISADVANTAGES OF LEASING:
1) You will always have a monthly payment.
2) Generally the most expensive option for a car based on cost per mile driven.
3) Read your lease carefully, you could be in for thousands of dollars in "reconditoning" costs at the end of the lease. I have seen leases that required the tires to have more than half their tread, or you have to purchase new tires. And you may be required to purchase the exact same brand and model tire. A co-worker had a scrape in a fender fixed on her BMW by someone other than the dealer. She had to have the work redone even though the body shop she used was actually better than the dealer. She also was told a broken window she had to replaced needed to be replaced again with BMW glass, not aftermarket. She got out of that when her lawyer dad pointed out that there was no BMW glass available.
4) Usually a mileage limit, or you race a charge for every mile over the limit.
GRAY AREA:
Tax advantage if car is used for business. Most people I know that used to lease for the tax advantage stopped because the IRS started disallowing all or part of the write off. But I don't know tax law to know if this is true, but I do know that most of the folks switched from leasing cars for business and keeping them 2 years, to buying cars for business and keeping them 7 years.