It's not shit for simply viewing an image from or even printing it at low res, but it is shit if you start editing it. JPEG is a compressed format and is not lossless, so you are leaving some of your image data behind when you export that image. JPEG has a lower dynamic range than a RAW image from the off anyway.
Technical stuff here if you're interested. [http://digital-photography-school.com/raw-vs-jpeg/]
Technical stuff here if you're interested. [http://digital-photography-school.com/raw-vs-jpeg/]
When you shoot in JPEG the camera’s internal software (often called “firmware” since it’s part of the hardware inside your camera) will take the information off the sensor and quickly process it before saving it. Some color is lost as is some of the resolution (and on some cameras there is slightly more noise in a JPEG than its Raw version).
The major actor in this case is the Discrete Cosine Transformation (or DCT) which divides the image into blocks (usually 8×8 pixels) and determines what can be “safely” thrown away because it is less perceivable (the higher the compression ration/lower quality JPEG, the more is thrown away during this step). And when the image is put back together a row of 24 pixels that had 24 different tones might now only have 4 or 5. That information is forever lost without the raw data from the sensor recorded in a Raw file.