What jpeg Cons or Disadvantages?

I presume you mean the popular form of JPEG; JPEG2000 addresses most of the problems:

The biggest problem is that JPEGs are lossy - when an image is converted to JPEG, some of the information in the image is lost. Professional photographers tend to avoid working repeatedly with JPEG images as continually loading and saving the image causes the image to lose quality.

JPEGs don't support layers - most photo manipulation software use layers; to save images as JPEGs the image has to be "flattened".

JPEGs only support 8 bit images. Modern digital cameras can operate in 12, 14 or 16 bit mode but if the images are saved as JPEGs, the extra information is discarded.