The only thing I noticed was that our rope twisted at the bottom, but it still creates the giant bubbles you see above. We purchases a big fancy plastic giant bubble wand from a rummage sale this spring and it's difficult to use. Once you try a couple times to make these bubbles it will be a cinch.
Another noteworthy thing is to make sure you have GOOD bubbles. A friend gave my daughter a huge container of store-bought bubbles as a gift and we tried using that at first and it was very frustrating. Then we made our own bubbles (much more economical, plus you can whip up a batch with things you have at home - that recipe will be the next post) and we made these wonderfully huge bubbles.