Shelley did not have any high opinion of Keats poetry, for it is frankly escapist and does not deal with current events, political or religious, as does the poetry of Shelley himself.
Keats kept of from the stirring events of the day: for him they did not exist at all. Keats’s poetry, therefore cakes human interest, and Shelley felt that his poetry, would never appeal to the common man, who is interested in his everyday life and wants it discussed in literature.
Moreover, Keats’s poetry suffers from a number of other well marked faults. For one thing it is too heavily overloaded with mythology. So many references to Greek literature and mythology are likely to confuse the average reader and present insurmountable difficulties for him. He lacked taste and artistic self-control. Their attention gets distracted between so many beauties and they fail to concentrate on any one of them. His narration is marked by too many digressions. The result is that his stories are thin, vague, and confused.