Absolutely yes! The 2009 DAT is the closest you can possibly get to the real DAT. More importantly, the scores you get on this practice test will almost mirror your real DAT scores. It is the most up to date version of the test with new question styles, especially in the reading comprehension section.
The 2009 DAT practice test should be the last practice test you take, and should be taken 3 days out from your scheduled test date. This way, if you are not satisfied with your scores on the 2009 DAT, you can still postpone your exam. Postponing your exam is sometimes the best thing you can do and there is nothing wrong with it. I postponed my exam for a few weeks, and I can confidently say it was the best decision I made while studying.
The ADA offers a web-based version of the 2009 DAT and a paper-based version. I strongly advise buying the paper-based version so that you can go back and review the questions multiple times. You can also review which questions you missed (the web-based version just gives you your raw scores with no review ability).
To stress why I recommend the paper version over the web-based version, read one of our user’s comments on the 2009 DAT web-based version: