The MacBook charger qualifies as both good and bad design, as some elements place it in one category, others in another. I usually tend to explain it as a great design with serious flaws.
The Good: MagSafe
Unlike most laptop charging cables, the MacBook cable attaches solely by magnet. If for some reason the cable is yanked (or tripped over, or gets caught on something...), it quickly detaches to prevent the computer from tumbling to the floor. I have been saved by this feature countless times and the MagSafe adaptor is one of the features of my computer that I appreciate most.
The Bad:
This charger also qualifies as a bad design due to it's stunning lack of durability. My first charger came with my computer and looked like this:
As can be seen in this photo, the plastic sheathing tended to detach from the connector and leave wire exposed. This was a very common problem, leading to a class-action lawsuit and eventually a redesigned charger. After mine became unusable, I bought the new design, which looked like this:
This eliminated a lot of the stress on the connector, but caused a whole new slew of problems. First, the connectors on a MacBook look like this:
The port on the left is where the charger cable attaches. When the cable is attached in one direction, it blocks the Ethernet and mini-DVI ports. When attached in the other direction, it tends to bend close to the connector, and the plastic sheathing begins to split. In my experience, these chargers (both the old and new design) have a lifespan of about two years before they need to be replaced.