I took the seminar ahead of taking the exam. I will say that I learned about some other materials that I had never been exposed to in my career. The only material that I was familiar with was regular old mild steel (ASTM A36, ASTM A527 Grade 50...etc.) and they went over Inconel, Monel, Stainless steels and other high alloy materials that require special attention when welding and inspecting. There were questions (metallurgy questions) regarding  these materials and I would have never been able to guess my way through those. Plus it reassured me regarding all of the self studying I had done prior. It is a lot of money to fork out, but to me it was worth it.

Will,

Are you asking about the online pre-seminar?  I did not but have heard it can be very advantageous depending upon one's background prior to taking it. 

I took the week long seminar the week of the exam and will definitely encourage others to do the same.  It was very good.  I just recently sat through one as our section rep and will testify that the new info and extra time for the Part B were very informative. 

He Is In Control, Have a Great Day,  Brent