Lian Yu wasn't terrible; it simply suffered from one deeply terrible moment. The issue is that the deeply terrible moment is supposed to be the hook for the next season.
You know it's going to be a great episode when Nyssa al Ghul [and] Slade Wilson makes an appearance. This episode took pages right out of Season 2 and Season 3's playbook, especially in the witty banter between Nyssa and Slade.
After a year of twists, turns, false flags and some seriously angsty drama, the Arrow season 5 finale is its most climactic and costume-heavy episode to date.