In my opinion at this point it is far better than senuke (but senuke is coming with a new version SenukeXcr with more features like adding more sites and platforms). The simple reason why UD is better is the success rate, ability to add/remove sites so lesser footprints and the cost associated. Above all with UD, you can be assured that they will keep updating the software regularly.
One area where senukex scores over UD, is the campaign management, where you can set it up and forget, and can created tiered links based on diagrams. Ultimate demon don't have that ability at the moment, they are planning to launch it in july.
Finally one area where UD completely scores over every other software is through offering a one time license at a reasonable price, cuts down your recurring costs..
Edit:
I see a lot of people comparing magic submitter with UD. in my opinion that is a valid comparison as senuke is far too costly to be compared with others. Magic submitter is very good, it is fast with a decent success rate.. it also comes with addons which you can add.. for instance rss addons are quite good.. However where UD scores over Magic submitter is with integration of article rewriters and spinners. TBS, Spinnercheif, Spinrewriter and other API integration. So for tier 2 links, you can pull in a related article in to UD, just through a click (seed article) and spin them using the spinners through another click, add urls, anchor texts in a easy way and blast them in a single click. This is an awesome feature which magic submitter don't have. It was me who spoke to Olex (creator of magic submitter) about integrating spinner and he added MAR which is not that effective.
The one area where Magic submitter is better the campaign mode.. where it is ultra easy to create new templates and the learning mode..
My verdict is if you are a beginner go for UD and if you are expert in this then go for magic submitter.