Touching it should invite you to open it or change it somehow. During the time that you're trying to let the puzzle know who's boss, you shouldn't get too frustrated. Some puzzles are meant for 'old hands' while other puzzles just let you dip your toes in to see how you like it. Everyone's frustration level differs. You want enough frustration to challenge you but not so much that you are discouraged.
Most people can do more than they think.
A great puzzle will stretch what you think your limits are. After you've finally solved it once, some puzzles may still take many more attempts to master. For example, a puzzle based on invisible magnetic attraction and repulsion will continue to be a challenge until you can develop a method that will minimize trial and error. Even after it is mastered it should still invite you to explore it more. It should delight you while you watch others try, in their own way, what you've already accomplished.