The idea of a demon servant fueled by kisses isn't too bad of a plot and has lots of potential when done right. Pity Her Majesty's Dog was NOT done right. It had it's moments but the female lead just got too annoying. She has this powerful ability to control people with her words but is such a meek and soft-spoken person that the fact she has this ability is moot since she hardly uses it. She had no inkling about technology, was pretty much useless on her own, and had the street smarts of a toddler. Her friend wasn't much better, if you've seen one meddling friend you've seen them all and this one is no different. She was incredibly nosy and suffered from the "I can't do anything because they said no" syndrome.
The demon guardian was the closest thing this manga came to a three dimensional character; you learned about his past, what made him tick, and got to read about him growing personality wise. He was aware of his faults and did everything in his power to be a good guardian and was not above asking for help when he knew he needed it. His rival wasn't all that well thought out and pretty much threw himself at the female lead. The only depth he had was the reasoning behind his compulsive lying and that's it.
The climax and falling action are so close together that it's almost impossible to define when one ends and the other begins. The resolution is hardly better. The ending, while well thought out, was disappointing. Had the female lead any backbone to speak of, perhaps the story would have been better.
I recommend this to people who actually enjoy the female lead to be naive and submissive. If you're like me, and prefer the female to have a backbone, go read Vampire Knight or even Inuyasha. Anything but this drivel.