I bought my first Mac in 2008 - a 15" MBP. I purchased AC on it, and boy am i glad i did. The nvidia card went out twice and had to get the logic board replaced twice - Apple actually gave me a NEW MBP when the mid 2011 ones came out.
Sold that computer shortly there after and bought my then new mid 2011 iMac - however i didn't purchase AC on it, since it was a stationary computer. BEST computer i have every owned. So rock solid. It is now over 5 years old, and i just bought a few month old 2.5GHZ MBP, and it has AppleCare until 2019.
Chances are you won't need it, but you have to be ok with the chance of something going wrong. I will get insurance on my computer, so if i am at a coffee shop and someone spills coffee on it, they will pay me what i PAID for the computer. I think it runs a few bucks a month, at least through progressive.