Unlike a guitar, the ukulele is tuned, so the notes are not in ascending order of pitch. This fingerpicking pattern plays notes in ascending pitch order. This creates a cognitive challenge as what you are doing and what you hear are at odds with each other. This pattern usually requires a lot more practice. If your ukulele is tuned with a low G (standard tuning) or a low D (baritone tuning), this will not be the case. It is still a pretty pattern, but you will not get the ascending pitch; therefore the aural challenge is not as tough.