Criticisms

* Unlike the video formats specified in international standards such as MPEG-2 and the format specified in the JPEG still-picture coding standard, there is no document that defines a single exact format that is universally recognized as a complete specification of “Motion JPEG” for use in all contexts. This raises compatibility concerns about file outputs from different manufacturers.
* JPEG has a relatively high bit rate for the delivered quality, requiring more storage space than more modern formats (such as JPEG 2000) for a given image quality.
* Since the development of the original JPEG standard in the early 1990s, technology improvements have made intraframe compression possible. Technology improvements can be found in the designs of H.263v2 Annex I and MPEG-4 Part 2, which use frequency-domain prediction of transform coefficient values, and in H.264/MPEG-4 AVC, which uses spatial prediction and adaptive transform block size techniques and more sophisticated entropy coding than what was practical when the first JPEG design was developed. As a result, MJPEG is an outdated and inefficient codec, whose main advantages are low processor overhead, ease of editing, ease of implementation by developers using existing JPEG algorithms or libraries, and broad compatibility.

zdroj: http://en.wikipedia.org/wiki/Motion_JPEG