MacBook – How does AppleCare Protection work overseas? (MacBook Pro 13 inch)

In general, extended warranty plans are a healthy-sized profit center for the company offering them. This implies that unless a product turns out to be less reliable than predicted, on average (mean average) customers will be better off paying for their own repairs without the warranty. However, if one can't afford to self-insure for abnormal or even normal deviations from the average, something like AppleCare will lessen the downside financial risks.

Thus, I suggest (and buy) AppleCare only if an Apple product seems to be getting numbers of reports of below average reliability (e.g. the Duo 2xx and PowerBook 5x00 product lines). For other Apple products, maybe put the money in a savings account instead, and there is a good likelyhood that you'll end up ahead after a decade or two of Apple products.

The built-in battery of your MacBook, MacBook Pro or MacBook Air is designed to deliver up to 1000 full charge and discharge cycles before it reaches 80 percent of its original capacity. Link.

Little differences in capacity are normal and are no indicator for a defect battery. Only contact Apple when your battery performes worse than the design capacity.