Splitting these blockbusters into two films has, for me, always been a negative development creatively, more of a cash grab than anything else. That said, considering how much material is being jammed into Batman v Superman--the film debuts of Wonder Woman, Aquaman, Flash, Cyborg, plus Lex Luthor, plus (rumored) Robin the Boy/Girl Wonder, not to mention, you know, Batman and Superman--it only makes sense to do this.
Judging by the titles, I can picture that the first film is mostly Batman with some Superman, ending with a big splashy intro for the other heroes, whetting audience's appetite for the next movie, a scan five five months later. This release plan was something Miramax did with Quentin Tarantino's Kill Bill, and while one could argue those films were overlong, I do remember thinking how fun it was after seeing the first movie that the second was just around the corner. If Enter The Knight ends with a quick debut of Jason Momoa as Aquaman, that would be very exciting, and could be really, really fun!