I did the kaplan tutor, which gave me access to the online course. I found the online materials to be amazing, but their effectiveness depends on how hard you work. If you do every excercise, watch every video, and take every test, you'll definately improve. If you don't, you can get your money back as long as you completed all the assignments. I spent 2500 dollars on my tutor program, but to me it was worth every penny, since a high DAT is the one thing you can really work at to get into dental school.
personally, I'd do the tutor again if I needed to, since it gives you access to the classroom sessions for free as well as the online materials. but if you aren't near a center, the online materials can still do the trick if you work through them and follow the syllabus.
thats my two cents,
will