It's by no mean a difficult puzzle, pretty straight forward, but the ideas are clever. Even if you're not a seasoned puzzler, you immediately know what you have to do, how you will do it and what you expect the result to be. But still you will have pleasure to solve it.
In the solution booklet Gary says to unscrew the bottle to reassemble all the things inside. But if you want a pretty difficult challenge you can try to reassemble it without unscrewing the bottle.
What is your favourite bottle puzzle?
To conclude: this is a nice puzzle and perfect for an exchanged puzzle