For the price, you can't expect to get an amazing bag, but this item is good enough for me. If you consistently do a ton of gigging with your cajon, maybe this isn't a good choice for you - in that case you should buy a sturdier bag for your instrument, especially if you transport the cajon in a car where it will bump into things.
The bag is thin, and as it is Millenium, it is of course by no means top quality. But for my use (occasional gigging and careful handling) it is good enough. I actually ended up buying some of these bags to store various percussion instruments in. I just put my small stuff like woodblocks and tambourines and shakers in there and use these bags to store them in my drum room.