The first two poems of this collection -- "Burnt Norton" and "East Coker" -- are among the greatest extended poems written in English in the 20th Century, or in any other century for that matter. The last two -- "The Dry Salvages" and "Little Gidding" -- contain, hands down, some of the worst episodes ever produced by any major poet, though these should by no means be included amongst the worst poems. The sins these later poems share in common are the related ones of flagging inspiration and patchiness, both of which can be seen as having their root in Eliot's attempt to take the 5-part prototype of "Burnt Norton," the first of the bunch to be written, and to will the others into being by using it as their model. If, however, this is failure, then we should all be so fortunate to be such failures.
Anyway, despite obvious flaws, "Four Quartets" is one of the landmarks of modernist poetry. Basically, the poems are meditations on time and eternity and, most importantly, the excruciatingly difficult task of trying to attain a little "consciousness" therein. Those, however, who feel no great kinship with philosophical poetry -- who indeed feel that poetry should express "no ideas, except in things," are perhaps never going to warm up to this collection. For those, on the other hand, who believe that poetry is one of the primary tools for grappling with the verities, then what else can I say except pounce on this collection? Oh, it's going to take many readings, much time and a great deal of thinking to plummet the furthest recesses of this profoundly great art, but then again what more could you ask for from poetry?
By the way, if you've never heard the recordings of Eliot reading these works, then you simply haven't lived.