Something that I just noticed that I had never notice before is the way itunes syncs changed items.
First we should recognize that itunes doesn't really imbed all the file info like description, ratings, artwork into each file. Itunes has its own database where it stores this info for each file.
I recently just decided to start ripping my entire DVD collection into iTunes. At first I made sure to give each movie a prober artwork and info like genre and year it was made etc... I now have decided to go back and add a description to them as well.
After doing this I noticed that for a minor change like adding a text description to the movie, itunes syncs the ENTIRE movie over to the ipad again instead of just updating the descriptions. When each movie is at least one gig in size this it a pretty big waist of time syncing all that info just for the added descriptions.
I have sent apple info about this to see if maybe they will fix it and though someone on here may also like to know.