Having studied T.S. Eliot for the first time recently as part of a 20th Century Literature course I would say that B.C. Southam's guide was indispensable to me. Particularly as I am a part-time 'mature' student who works full time and I don't often have the luxury of spending the hours that I'd like to look over academic articles and sources.
Eliot is not the easiest of poets to understand (...let alone master), his use of allusion and his 'elitist' approach is quite intimidating to any new student...I wasn't the only one on the course that had trouble with him! - - B.C. Southam was recommended by my tutor as a highly respected and much revised guide for undergraduate study.
Don't get me wrong, you can read Eliot's poetry without Southam's guide and appreciate the vivid imagery, the construction of the 'free-verse', the amalgamation of poetic forms and the way the poems sound/feel when you read them. But Southam's guide adds the historical context, a path through the dense allusive material & helps you to understand the depth of literary history contained within the poems. It also explains a little bit about the modernist principles that guided Eliot as a writer and the influence wielded by his family history, his student days, his unhappy first marriage and his mentor Ezra Pound.
I could not have studied Eliot effectively without Southams's guide - this is why I feel the book deserves 5 stars (...that and the fact that I got far better marks than I had expected!).