I own a Great Dane, and I gotta tell you, these bags work GREAT! Even though he's a big as he is and so are his clean-ups, these bags do the job every time! No tearing, no spillage, closes great! Couldn't ask for a better product.
Bottom line: Biodegradable poop bags are a convenient option, which sometimes you just need. If you're out backpacking or walking or visiting friends, you might not be in position to compost or flush the waste. In those cases, a biodegradable bag made from corn is the best possible solution.