It is difficult for anyone else to help you with this question, because it asks your own personal opinion. This means there is no right or wrong answer – it is simply what you think about the poem. There are a thousand different reasons the poem might appeal to any one individual, and no one can tell you what you like about it but you.
That being said, I can outline some of the more striking characteristics of the poem. First, the image the poet conjures of thousands and thousands of yellow daffodils swaying in the breeze along the shores of a bay is stirring, to say the least. And it is a beautiful concept, the idea of simply stumbling upon such a sight as one wanders through nature – an example of how life can reward you when you least expect it. The field of daffodils is also a good example of how the smallest pleasures and surprises can have the strongest lasting effects on us, as human beings. The speaker notes, “I gazed – and gazed – but little thought/What wealth the show to me had brought;” he was very taken with the sight of all the flowers, but he could not have predicted the extent to which it would affect him, for much later, “in vacant or in pensive mood” – in those little idle moments of the day – he would think back to that sea of daffodils and the thought would make him happy. This is a wonderful, calming thought – that such small events can leave such lasting traces on our hearts.
This is a poem about the beauty and the healing benefits of nature, about how it never ceases to surprise and delight. Even in the midst of our most vacant wanderings, we may stumble upon some bit of life that has a positive effect on us. The poem is very hopeful, full of vivid imagery that, much like the daffodils themselves for the speaker, becomes imprinted on the brain, and can often be revisited for a smile or a thought of peace.