About a year ago, when I was two years into my warranty, I brought my rMBP to the genius bar because I noticed a very small cluster of dead pixels. Apple replaced the display under AppleCare. Without my warranty, the charge supposedly would have been $ 623.86 (an amount I definitely would not have paid).
As mentioned above, the decision is up to you. In my case, after spending $3,004 on my 2012 rBMP, $239 for AppleCare (I bought the AppleCare with a student discount) was a no brainer, and for me the warranty was well worth its cost.
You will find people who have Apple products that work fine for 5+ years without a single issue, and people who have multiple things go wrong in a 3-year period of time. In my case, I've had enough AppleCare warranty experiences that I tell people close to me that it's a bad idea to go without it. I've definitely bought four-year warranties for TVs I've owned, and didn't end up using them, but for every Apple product I've kept for three years (maybe not my Mac Mini), I've used it. My girlfriend's brother had a white plastic MacBook, and a few months after his one-year warranty ended, something on the logic board broke and he couldn't charge the MacBook. Replacing the logic board was going to be some ridiculous amount of money, and he had to turn the computer into a media PC.
That said, I think the more money you spend on an Apple product, the more it makes sense to get AppleCare. I probably wouldn't get AppleCare on an iPod touch, but I did on my iPhone, and I would on a $1,000 MBA.
I can't speak to the effectiveness or ease of using a credit card extended warranty on an Apple product, but maybe someone else can. Whatever that experience is like, I can't imagine it being better or more pleasant than going into the Genius bar and getting your computer back sometime within a few hours or days.
