Nothing's perfect, but it's better if it's made using some metal for casing, believe me! For example, I never heard about MacBook Air case cracks, but the white MacBook cracks are already notorious. For some users, this problem was enough to bring Apple into court, since the Cupertino-based company refused to fix the defective laptops without adding some extra charges, despite the fact most of them were still under the warranty...
Now, things are headed in the right direction, since I am sure there aren't many fools working for Apple, and most people in charge of handling customer support know that customer satisfaction is the key to success. In fact, I guess this is something most customer support employees all over the world know, only that some of them don't act accordingly - no examples here, sorry, I am sure you got some, so feel free to share!
The story still goes a bit in the shadows, because - at least according to AppleInsider, "Apple is privately acknowledging an issue with the enclosure on some of its white 13-inch MacBooks, which in some cases have seen the formation of hairline cracks during normal usage patterns."
The best part of it all is that, if Apple retailers are unable to identify signs showing that the cracks are the result of user's actions, the notebook should be sent to Apple, no matter if the 1-year limited warranty has expired or not. Pheew!
Anyway, if you don't have a MacBook yet, or simply want to get a new one, my advice is to spend a few extra bucks and grab one having the new aluminum unibody case.
