DDS was given to print press at the show, but not demoed. someone recently posted impressions of a demo that came with a dengeki magazine in japan.
there's a 2 page preview of DDS in the kingdom hearts GMR, if you're looking for some coverage and happen to get/have access to that magazine.
SMT3 is more gameplay focused, and DDS is more story focused, trying to wow the FF audience. granted, they both have good stories and good gameplay, but the balance is different. of course, final judgment awaits the review copies.
SMT3 will be out in september in the US. DDS supposedly will be out in november but i don't think that's rock solid.