It's a good class, they cover a bunch of stuff outside of car wrapping. From my experience you get out of it what you put in. My advice would be to make sure you have a firm grasp on all your other vinyl installs, wall graphics, floor, premasked, etc. The more time you can spend on the car wrap portions, the more value you'll get out of it. What you're paying for is time with a 3M installer, so always ask them questions and stay engaged with them. Even if you think you know the answer, they might have a different take and it will at least start a dialogue. There's usually a couple people that are there to be certified, you'll find this out in the first day, but keep note of who those people are. If the 3M guys are busy and you get stuck, don't sit around, ask those guys and then confirm it with the trainers when available.
I could've have gotten a lot more out of it. Having never touched vinyl to a car myself when taking it, the 3 days fly by and at the end I wasn't at the point I hoped to be but it was my fault for not engaging myself enough.