All you NAPP members out there, check the Lightroom section of your latest Photoshop User magazine (March 2009) for MY article on DNG!
For those of you who aren’t NAPP members, you’ll want to sign up now!!!
In the meantime, here’s the main bullets points directly from Adobe Lightroom 2 – The Missing FAQ
DNG files are generally 10-40% smaller than their original proprietary format, depending partly on the size of the preview that you choose to embed.
Proprietary raw formats have their XMP data stored as a sidecar XMP file, whereas DNG files have that information embedded within the single DNG file. The question is, do you find sidecar files a pro or con?
Long Term Storage
The DNG format is openly documented, which means that it should be supported indefinitely, whereas proprietary formats such as CR2, NEF, RAF etc. are not openly documented. Will you be able to find a raw converter in 20 years time that will convert a proprietary format when that camera model is ancient history?
Most manufacturer’s own software will not read a DNG file, only their own proprietary formats. Do you ever need to open a file in the manufacturer’s own software? If so, you’d want to embed the proprietary raw file – it can be extracted use the DNG Converter tool, however it does negate the file size benefits.
While there is DNG support for MakerNotes, some manufacturers don’t stick to the rules, and therefore MakerNotes embedded in an undocumented format can’t always be carried over to the DNG file, however if you’re not sure what the MakerNotes are, you probably won’t miss them.
Check the Photoshop User article for lots more pros, cons and how to’s.