Don't let the good price deceive you! In my opinion, this is a quality gym bag.
Firstly, I liked the size of this duffle. It's large enough to hold your gym shoes, a change of clothes, your water bottle, and a towel. If however, you need to carry quite a bit more that that, a larger bag might work better.
Secondly, I would vouch for the strength and durability of the bag. I haven't had the bag for too long, but I took a good look at the seams and even pulled at them to see how well sewn they were. They were very straight and tight. I expect it will last long and hold up great.
Thirdly, I was impressed by its design. There is a hard sheet of plastic in the bottom of the bag. This helps the duffle keep its square shape, (so that all of the weight of your items don't fall to the center of the bag and get disorganized). That's probably a pretty standard design for a duffle, but its worth mentioning because its a good design that works well.
So, simply put, I am very happy with the size, durability, design, and price of this duffle.