Wordsworth's poetic output is large, spanning the years 1785 to 1850. Studying his poetic development is rendered somewhat complex by the fact that he continually tinkered with his works, so there may well be several versions of the same poem. The Evening Walk, for example, underwent several revisions between the date of its publication in 1793 and Wordsworth's death in 1850. The case of The Prelude is even more complex, there being now three versions of this work dating from 1799, 1805 and 1850, though the poem was never published in his lifetime. The two early versions have been reconstructed from his papers by scholars in the 20th century. The rationale behind this is that the 'improvements' Wordsworth made to the poem, after 1805 in particular, are not, in fact, improvements at all, but rather take away from the vigour of the poem.
It is interesting to note that Wordsworth's early poems (in particular An Evening Walk and Descriptive Sketches) are full of the faults of exaggerated 'poetic diction' about which he complains in the Preface to Lyrical Ballads (1802), but he nowhere refers to this fact. It seems to me that an honest man would have at least mentioned the fact that he was himself at one time misled by these ideas, but Wordsworth does not. It might seem a trivial point to make, but this is a leitmotiv which colours Wordsworth's response to many important issues (for example his relationship with Annette Vallon after his return to England, which is by no means a trivial matter, though it is treated as such by most commentators). Somewhere deeply embedded in these deceptions is his refusal to admit that he is, or even was, wrong, and it is this, among other things, that weighs upon him as time goes on, eventually destroying his manifest genius. His increasing celebrity after 1805 accelerates the debilitating effects of this fault, producing a hesitating, fearful and indecisive old man.
It is remarkable that, despite the evident faults of the early poems, his imaginative genius, based on accurate observation, still shows through, or, as S T Coleridge puts it, the effect of: ...the fine balance of truth in observing, with the imaginative faculty in modifying the objects observed... (Biographia Literaria, Vol I p84).