Our speaker never gives himself a name, or even gets too specific about anything at all. But yet, we learn a lot about him in this brief poem.
For one, he likes a well-made suit (at least we can assume, otherwise how would it last so long?). He takes a shower every morning. He likes to take walks and meet people, because he believes that the struggles and events of daily life make him a better poet. He has an enemy or two, the type that might want to assassinate him. He sometimes thinks of his soul and his mortality.
The poem is taken from a collection of odes, all of which address everyday objects. The speaker in Ode to My Suit has an appreciation for the things the suit allows him to do, and he also sees that these everyday objects can be used to consider much larger topics, like spirituality, joy, death, love, or fear.
Now, it's never a good idea to confuse a poem's speaker with its author. After all, a lot of poems are written from the vantage point of invented characters. That "I" you're reading, then, may not be the poet talking. In the case of this poem, however, it sure seems like the speaker and Neruda are concerned with the same things. They're as united as the speaker and his suit.