Yep, that is how it is suppose to work. And since yours is not working that way, we are trying to help you with some trouble shooting techniques.
Have you looked at the Raw Fine Tuning Brick in the Adjustment Panel? Click the Gear Menu and make sure Apple Camera Default is selected. If the Apple Camera Default is not checked, after choosing the Apple Camera Default, also choose Save as Camera Defaults.
If you are still having problems, it could be a software problem or a camera hardware problem.
If you have PS Elements or better, they will open RAW files. See if they have the same darker look. if you do not have a PS program that reads RAW files, check out Raw Photo Processor. It is a free Mac app and does a better job at tuning files than many of the other software packages. Again, check for the darker look.
If the other packages also have a darker look, likely the problem is with the camera. If not, the problem is either with Aperture or a bad "default Camera Raw File Reader" file from Apple. iPhoto has been able to open Raw Files for a few versions. See if you get the darker look in iPhoto. if so it is likely a problem with the file supplied by Apple to read the camera RAW files. Since other people with your camera, do not have this problem, likely one of your files got torqued. I can't think of an easy way to replace a single Camera Raw Reader file. So, if you reach this point, I would hope you would still have some AppleCare coverage and call Apple.