First, Wordsworth uses the Italian sonnet form in order to express his feelings about the beauty of London first thing in the morning. An Italian sonnet is composed of an octave (group of eight lines) and a sestet (a group of six lines) and has an end rhyme scheme that follows an abbaabba cdcdcd (or cdecde, or something similar) pattern. The octave might present a question and the sestet an answer; or the octave could pose a problem and the sestet a resolution. However, the most typical sonnet subject is, in fact, love, so the fact that Wordsworth uses the sonnet form to praise the city of London could be interpreted as just one more way he shows his positive feelings about the city.
In the poem's octave, Wordsworth declares that there is nothing on Earth "more fair" than the sight of the city at sunrise. He personifies the city, describing it as wearing "the beauty of the morning" like "a garment." We can imagine the golden sunlight reflecting off the "Ships, towers, domes, theatres, and temples." He says that they are "bright and glittering in the smokeless air," almost like jewels on the metaphorical garment the city wears. Given that he's described the sight of the city as "its majesty," he also seems to compare it to a queen.
In the sestet, Wordsworth moves on from this personification of the city and personifies the sun, gendering it male and saying that not even the sight of the sun on natural formations (like "valley, rock, or hill") is as "calm[ing]" and beautiful as the sight of "his" light on the city. The river, too, is personified, gliding "at his own sweet will." Even "the very houses seem asleep; / And all that might heart is lying still." The city is personified, ultimately, as possessing a heart. It is as though the speaker is so in love with the city that he imagines her as a beautiful, even royal, lady. Everything is personified because it all seems to possess so much life. It is clear, then, that the speaker truly loves this city.