Perhaps the biggest downside of online learning is that you need to be self-motivated. You actually need to log into your online course and find a time to listen to and engage with the material. This can be challenging for many people, especially if they are studying in a place with distractions (like home).
Additionally, people sometimes need that in-person relationship with an instructor and other students to really understand the material. Indeed, there are also limitations with technology that can interfere with your ability to complete an online course.
Furthermore, you do need at least a minimum level of computer literacy to complete a course. Fortunately, nurses now have to utilize computers every day to perform their duties in acute care, so all nurses should be able to navigate through an online course.