I wouldn't feed it either. However, I've known adopters who needed to select a food they could find at Walmart, so I've looked at the ingredients of the line to figure out the best option in it--for these adopters, I recommend the Purina One Beyond over the regular Purina One, as it has better ingredients (in my opinion).
My view is that the regular Purina One is undesirable because of all the corn in it (corn is an ingredient that many GSDs seem to not do well on, in my experience); Purina took the the corn in the Beyond.
If you need an economical food, do you have access to Costco? Costco's Kirkland food is in the same price point I believe. It's made by Diamond with an ingredient list that looks a lot like Taste of the Wild. It's a four-star food on DogFoodAdvisor.com: Kirkland Dog Food | Review and Rating
If you're on a budget, get at least a 3.5 star brand. Costco has Kirkland and Walmart has Lamaderm and Pure Balance. They're both reasonably priced. You don't need to feed your GSD super premium dog food but stay away from dog food that has corn, wheat or soy in the ingredients and which has junk fillers. You don't need to feed your dog the most expensive dog food but the cheapest dog food isn't necessarily a good buy. Go for the happy medium and in 4 star foods, Fromms, Merricks and Canidae won't break the bank. You want your dog to be healthy and happy and that is the only consideration in selecting its diet.
Remember, what you feed is what you get. All the extra yard cleaning is stuff you bought. Best for the dogs and your wallet is to feed good quality. I know alot of people have a hard time spending the extra because they don't realize the difference in their dogs til they change to the better food, but if explained that they're literally throwing their money in the toilet they seem to be likely to change to a better quality.
Many years ago, when I was younger and I didn't know better, I fed my dogs Purina. I used to switch between Beneful and Purina One thinking I was giving them "good food". I cringe now just thinking about it! They had such terrible allergies one of them was almost bald on his belly and his tail, and poop wise it was awful too.
I feed one of mine Purina Pro Plan. I tried many high rated dog foods and spent a lot of money on testing for various conditions. Pro Plan was the only food that got rid of his chronic diarrhea. I've tried a couple of times to switch him to something of "better quality" and it never works. I just stick to what works now.
He has great coat and skin. It just seems to work for him and when you've had a dog with chronic problems (especially diarrhea) you will stick with what works if you're lucky enough to find it.
My other dog has an unknown food allergy and she does great on Fromm. It looks to be a much better food than Pro Plan and it works for my female but not my male who is on the Pro Plan. I won't rock the boat. They're both happy and healthy.
I do agree with other posters that Merrick seems like a good food so if you're dog is doing well then I would just stick with it unless there's another reason you want to switch.