I don't think anyone can make a judgment about Petsmart training as a whole because the quality of training really varies between the stores.
There are some stores that have a real training area in the back and then there are stores where the "training" area is a little cubicle by the front door and most of the actual training is done in the aisles of the store. Some Petsmart stores have really good trainers, in other stores the trainers are Petsmart employees with limited training who are the designated "trainers".
What I would do is go and observe the training classes at your local Petsmart and make a decision based on that. I would also ask about the requirements for participating in training. Most training places ask for proof that your dog is up to date on all shots.
One thing that I would look at is the space question. At my local Petsmart, classes start in the cubicle up front. It's a small square area with chairs right next to each other, and during talks from the trainer the dogs are literally on top of each other and sometimes behaving quite inappropriately. I know a lady through another forum who was asking how to best ask the people sitting next to them that she doesn't like their dog humping her puppy because she felt it was not appropriate but wasn't sure if she should say anything because the trainer seemed to have no problem with it.
In our Petsmart, much of the class work such as heeling, sit, stay, etc. takes place in the aisles of the store. In my opinion, that's not a good place to train. They consistently get interrupted by shoppers needing to get past with carts to do their shopping, and shoppers' dogs who have no part in the class. It also exposes the dogs that are being trained to strange dogs just visiting the store while shopping with their owners. Those dogs aren't necessarily well behaved, friendly, or healthy, either. I'm not sure I would want that in my training environment.
Your Petsmart may be different - I don't know, I have not been there - but I would never train at mine.
There are a lot of Maryland members on this board, so hopefully someone will either be familiar with your Petsmart or can recommend a better training facility that won't break the bank.