This poem is quite a short one but it's effective with regards to the subject matter.
There are some issues with the grammar, for example every line begins with a capital letter but not every line ends with a full stop.
The second line of the poem uses the word "main" where it should read "mane".
What the poem lacks in complexity it makes up for in heart, it is a frank poem about the beauty and grace of the mustang horse and this is conveyed nicely.