In this monologue, Tennyson's Ulysses expresses his worrings and nostalgia at his return to Itaca. In particular, he complains about his citizens, who are not refined, and his wife, who has become old, and realizes he's being idle, because his voyages with his companions are finished. Adventure is indeed life to Ulysses, so he won't be able to sleep in idleness.
There are several devices used by Tennyson to convey the idea of struggle between the dramatis personae and his destiny. Tennyson's choice of words is important to the analysis: "idle", "still", "barren", "mete", "dole", highlight Ulysses's sorrow and emptiness; on the other hand, words such as "life", "enjoy'd", "scudding drifts", "hungry heart", "much have I seen and known", "experience" emphasize his nostalgia of gone times.
It is important to notice that the speaker's "I" is always in a strong position, to remind that the "I" is the strongest part of an hero.
The exclamative marks highlight Ulysses's determination and self-realization about life.
Ulysses's ultimate goal is knowledge, as stated in the line "To follow knowledge like a sinking star": the simile best describes the difficulty to follow knowledge, which is hidden.