I still remember Peterson as a young writer, writing increeeeeeeeeedibly basic articles for utter noobs, way back in the day (1980's). I still cannot get over the years-long impression seeing his stuff every month created in my mind. I know that's not fair to him, and he's been around a long, long time, and now he's on the interwebs, but when a first impression is made over multiple years, it tends to stick. LIke for example, I just can NOT and NEVER will be able to take Steven King as a "serious" writer...instead, I think of him as played in the old Saturday Night Live sketch, as a guy sitting at a typewriter, and who just bangs out tripe at breakneck speed, just vomiting out pages and pages worth of dreck, non-stop.
This is totally unfounded,and maybe it's unfair to say, but I think you'd
get more and longer-lasting value out of any one of a hundred $3.99 books on photography available at any Goodwill store anywhere in the US. Not trying to be disparaging to Peterson, but the thing about seminars is there's always some people who the material is too basic for, and for others it's too complex, and for hopefully the majority of the audience, the material is at their level.
He does know how to shoot great photographs that have mass appeal:
2015 Workshop Schedule: Bryan F Peterson Photography Workshops
Not knowing how much or how little you know, it's difficult to say how much you'd get out of attending his seminar. It is a way to get together with a bunch of other people with cameras, and maybe rub some elbows with others, and hey, at today's prices for stuff, $69 is NOT that much money. He does have a long history of pragmatic instruction in, "You wanna make a photo like this? Then do this and this and this," level of instruction.