I like that it is open source software with many options available to make your life easier as an administrator of this tool in our organization.
It has been very easy for me (and my team) to pick up right away because there are so few things we need training or support from them about how best use their product. We have used other products before but none had all these features combined into one package at such low cost! There really isn't anything specific i dislike now - just everything else they offer makes us want more!! You can do almost any type of document management you could possibly think off using XMl Director's tools.