There are three basic reasons why I'm pleased to have started using Deep Meta.
1) Categories and keyword disambiguation is all on one pages and much easier to navigate than on the site itself. Even if someone didn't use it for any other reason, that makes this ticking and clicking less painful. You can see all your words and all the sub-catagories, on the page, unlike drop downs on the IS site.
2) Batch uploads. Click it and forget, everything is smooth.
3) Release attaching is easy if you have a batch of the same.
Something to beware of, unless it changed, you can't add releases or alter them, once you upload. Say you upload normally and add a release with DM, it might get lost. Say you upload DM and add a release on the site. Somehow it's whacky. Do them at the time of the initial upload. Make changes after acceptance.
4) Keywords, IPTC, cut and paste easy from DM one image to another. (and as mentioned, always finds everything)
I could say the main reason for using it is better, more user friendly navigation and IPTC editing, with the bonus of batch uploading ease.
I don't find it that useful for data or stats, might be I'm missing something. I still watch those online. Maybe that's why the plugins?http://www.istockphoto.com/forum_messages.php?threadid=352385&page=1
Sean wrote everything else useful on that site!
Probably why I though so
Very impressed with DeepMeta - sure takes a lot of the pain away and even recognises ALL the IPTC unlike the main site