I didn't think it was useless. It may not be super realistic when compared to the actual DAT, but it certainly isn't useless for this reason:
It asked me random questions, the majority of which I had never seen/heard before.
Perhaps the questions were too easy, but still they asked me to review the material. It is one thing to make up your own questions in a flashcard type manner, or to quiz yourself. It is completely another thing to have somebody else ask you questions that they thought up.
When I was preparing for the DAT I viewed ALL practice as GOOD practice, even if the questions were too easy or not realistic. At least they got my brain cells working.
I wouldn't center my studies around that Kaplan CD, but I would use it to review material or gauge my progress to an extent.