You are going to get varied responses, but IMHO, yes - it means 3 years of coverage beyond just the keyboard, also for accidental damage (which can happen with any mobile system) (there is a deductible), plus it covers battery replacement if you can drive your capacity down to 80% within 3 years (quite doable if you are doing a cycle or more a day.)
Thus far (and excluding all active systems I have with AC), my investments in AC and AC+ have probably saved me more than it has costed.
So it is my humble opinion that, purchasing AppleCare and using the device without over-babying it can be a good way to go.