Her Warrior King is not your typical medieval romance. Politics take center stage as the English and the Irish clamor for the same land. Patrick will do anything to save his people, even marry one of the loathsome Normans, but that doesn't mean he has to love her. He plans to keep his heart his own, but his bride Isabel has other ideas.
Patrick is an interesting hero. He was not the original king of the MacEgans: his older brother was before he was slain by Normans the previous summer. By decree of the people, he has stepped into his brother's shoes, and it is understandably very emotional for him. His transition from a warrior to a king is gradual and fraught with tension. He's sympathetic, honorable, and kind in his own way.
I say "in his own way" because he is an absolute monster to Isabel. He often forgets about her to the point where she goes without fire, food, and blankets for extended periods of time while he tends to his kinsmen. From the beginning, he keeps her at a distance by literally keeping her on an island away from his people. Patrick is a fantastic character. Given more pages, I think his transformation into a lover would be believable. As it is, it's hard to see him as a romantic figure when he's just so cold towards Isabel. Sure, we get to see his perspective, and we readers know how much he desires his wife, but it doesn't play out on the page.
Because Patrick doesn't have the space to mature, Isabel is doing all of the work in their relationship, and he does not deserve her. The woman literally swims across the stream to be with her husband who has repeatedly spurned her. She is a saint because she can see how hard he's trying, and she still thinks "yes, I want a piece of that". That said, it does make her frustration with him sometimes a little unreasonable. She knows how difficult his role of king is, and yet she repeatedly asks him to give it up for her. What she's really asking is to be included in his family and his clan, and she does voice these desires. It's a minor thing, though.
I think a good phrase for Willingham's novels are "down to earth", literally in some cases. These characters, despite being kings and queens are not wealthy. There are no jewels or glittering gowns in her novels. They're grappling with complex issues in a brutal time period. It's just, because Willingham is writing for Harlequin and her books never reach 300 pages, her characters don't have the time and space to really mature. Their growth is almost spontaneous, which can give the impression to some that Willingham's subject is shallow. I don't think it's shallow, per se. Just rushed.
Overall, if you're looking for a romance that's more grounded but still spicy, then I would recommend this book. It's not my favorite in the series, but it's a pretty solid addition.