Is it worth buying a used W140?

What is your question?

Hello I am 24 years old. For the past 5 years or so I have admired these w140's. I love the quality and build and styling of these cars? I have found a nice all black 1999 s420 with 150,000 miles for a great price, only thing is the check engine light is on and the dealer has not put in money into the car. Would I be taking a gamble buying this car for a great price. What would the yearly upkeep be even if I just drove it on the weekends. Thanks