My Review (No Spoilers)
http://nimareviews.blogspot.com.au/2016/07/sing-street-movie-review.html
shareI loved this film however I understand your minor criticisms... I would add that in addition to the relationships between Conor and Raphina and his brother(not a threesome), I enjoyed the bond between Conor and, as you wrote, Lennon to his McCartney, Eamon. In fact, the scenes depicting the collaboration between Conor and Eamon were reminiscent of the stories of John and Paul in Aunt Mimi's living room.
Keep up the good work!