The narrator of the poem describes a typical Romantic revulsion with the everyday world, one that is `too much with us.`In Keats`case, his extreme poverty and illness no doubt exacerbated this reaction.
The narrator seeks forgetting (Lethe, the river of Hades, which causes loss of memory) or escape. One road to escape mentioned is opium, another mentioned is wine or even èaseful death`. The song of the nightingale, and poetry, are finally presented as an alternative way of escape, in a manner thematically similar to other works of Keats (e.g. the realms of gold of Chapman`s Homer)
yes keats is escapist. he escapes from grief and sorrows to joy. he engulfing his grief with the enchanting music of nightingale.