There's a reason this ballad is so celebrated. It was surprisingly readable, despite the deliberately archaic language. Even though I've historically loved Romantic poetry, I was procrastinating my preparation for teaching "Rime" because I suppose I discriminate against maritime narratives, I suppose? But this supernatural quest is wild, and Gothic as hell. I'd recommend taking a look at the original version, first printed in 1798's Lyrical Ballads for Gustave Doré's intricate Romantic realist illustrations. 
Some of the annotations are useful, particularly in drawing connections between different parts of the poem; some annotations particularly relating to critical intepretations, weren't as relevant to my purposes. I skimmed the Intepretations section at the back.