I guess it depends on the Petsmart.
I have my puppy there- we're in the Beginner Class and the trainer has been really helpful. This *is* my first puppy, so I guess it depends on your own level of expertise. If you've had dogs before, the training class probably isn't for you. But since I haven't, it's working really well for me- I needed some guidance.
It's all about positive reinforcement and we've used the clicker since day one. We also talked a bit about nutrition, which was super helpful for me.
Oh, and when I adopted her, I got a coupon for training- so it worked out to being $10/class for 8 weeks. Not bad, imo.