I took two of my previous dogs to PetsMart, but then chose a different option for my current puppy.
My first experience was actually when I was in middle school, and it did a decent job of teaching me to teach my dog. As a female middle school student with a 85 lb dog, I was able to walk him around the subdivision by myself, which I thought was pretty good at the time.
My last experience kind of soured me on petsmart. I took my last dog there and just felt like they were constantly trying to sell me stuff. They are a large chain store so they are out to make money in the end. I think a lot of it has to do with what trainer you get. I don't feel like I got near as much out of it. I've found an issue where the trainer(s) at petsmart will teach you their normal by the book way to train the dog, but if you have any issues or your dog is more dominant, decides to be stubborn, or sometimes the owners personality just doesn't work with that specific style, they don't really have the in depth knowledge on how you should work through it with the dog and owner.
This time I took my dog to another facility, where I was invited to come out and watch a class, they were willing to provide contact information for other clients they had if I wanted to talk to them, and overall just came across as more open. The price of the class also included all training equipment (leash, collar, treat bag, etc). If I decided to change collar types or anything he wanted me to come back to him so he could make sure I understood how to use it and fit it correctly. When I got frustrated with something during practice at home I could e-mail or call him and he always responded and provided hints and specific ideas based on my dogs personality. I don't recall any of my petsmart trainers being that open or knowledgeable. My trainer said he actually took one of his more stubborn dogs to petsmart just because he wanted to see how and what they taught, and he found much the same as I did they if your dog wasn't catching on with "their" way, they didn't individualize it for that dog and trainer or know how to help you work through your specific issues.
Overall I think petsmart is definitely better than nothing, and a lot of it will be based on who your trainer is. I personally think there are better environments for training, but a lot of it depends on where you live and what options you have. All in all I would look more into the specific trainer, and not the place (How much experience do they have? How much experience do they have with your breed? What type of certifications and/or affiliations do they have? Did they have to be invited to where they trained, pay a lot of money to get trained, or were they just in one of those train the trainer classed?, etc). If your comfortable with the trainer and how they teach, than that's the important part.
Sorry didn't really plan to be that long winded

. I just finished with one of my best training experiences ever, and apparently am super passionate about this at the moment. Good luck with Puppy Class!