Overall I liked this supplement, but I feel that it's overpriced.
The new Silvermane Exemplar is very detailed, covering more than 5 pages of the document, and the Oath of Greenwood and the Elder Unicorn Bloodline are well detailed including the appropriate level features for each.
However the Pact of the Sundered Horn feels incomplete. This Warlock oath is covered in only two or three paragraphs and there are no features defined for the pact, only that the warlock adds necrotic damage in some situations and that a unicorn warlock gains a bite attack but loses all benefits of its horn.
[3 of 5 Stars!]