No, Rush E is not the hardest song. While it does have some challenging sections, there are many songs that require even more technical prowess and finger dexterity to play. The difficulty of a song depends on each individual musician's skill level and experience with playing the particular instrument being used for the piece. For example, a skilled guitarist may find Rush E to be fairly easy, while someone new to guitar may find it quite difficult. Ultimately, everyone has their own opinion about which songs are most difficult - so if someone believes Rush E is the toughest around then they should go ahead and enjoy it!