Veritas was a really really effective GMAT prep course. Both the lessons and the sample test sections were a big help, as were the diagnostic/analytic components of the online test (e.g., data on pacing, etc).

Would highly recommend it! The materials were really really helpful, and I found that it gave me the exact kind of preparation I wanted in advance of taking the course. Moreover, the multiple practice tests gave me plenty of opportunities to perfect my test-taking strategy (pacing, emphasis placed on easier vs harder questions).

There are some slight drawbacks to doing an online course rather than a live one, but I don't think the extra benefits of doing it live merit spending the extra money.