Final answer:
Users of the free version of Duolingo face advertisements, lack access to enhanced features like new quizzes and offline lessons, and must decide whether the premium features are worth the subscription fee.
Step-by-step explanation:
The free version of Duolingo presents several hurdles for users compared to the premium subscription. The first hurdle is the presence of advertisements during language practice, which can interrupt learning and reduce the overall user experience. The second hurdle is the lack of enhanced features that are available in the premium version; these include new quizzes and the convenience of saving lessons for offline use. This means that users of the free version cannot enjoy the full range of Duolingo's educational capabilities that can aid in more effective language learning.
Lastly, the absence of a subscription fee for the free version, which is the cost paid to remove the aforementioned impediments, constitutes a hurdle for individuals unable or unwilling to pay. While the basic functions of language learning are available, the free version does not provide the same comprehensive and uninterrupted experience as the premium offering.