American Sign Language, like all languages, is a language and therefore different from English. The parent language of ASL is actually LSF, langue des signes française, and the parent language of LSF is French. There are also other influences on ASL such as home sign, Martha's Vineyard sign language, and the sign languages of the indigenous populations of the Americas. Therefore, to say that ASL is just like English or easy because it is similar to English, is false.
In some ways ASL is difficult to learn. If you were to take another spoken language your working memory still works in the same capacity. However, by taking ASL your working memory does not function the same way because you are not working in the visual-spatial modality (Williams et al., 2015). This means that a students' ability to retain information is shorten.
Since an ASL GLOSS can be created to give a written transcript of signs, it also becomes difficult for students because they want to write in English but they actually have to write in ASL GLOSS. In addition, when students freely sign, they tend to follow the English sentence format and not the traditional, ASL sentence structure.
Although components of ASL can be easier than Spanish or French, ASL is not automatically the easier language. You will still need to work hard, study, and practice.