Not been on a TI course, but I've read up on it, and got myself a book, and have spent the last couple of weeks putting it into practice. IT IS WONDERFUL!!!! I've gone from dying after 2 lengths of front crawl to today's hour non-stop (56 lengths!) entirely FC. I'm still going to go to a stroke-improving session, but I reackon you can make a pretty good start yourself. So, I love TI, but not absolutely certain whether a weekend course is necessary.