I like the message, I don't like the colour, I like the font, I don't like the way it's laid out... all feedback we've heard a thousand times.
Your agency shouldn't be interested in whether you like it, they should, however, be interested in whether or not it works as a piece of communication representing your brand. Whether it's getting across the right message about the product to the right audience.
No brief should never say 'I have to like it' but every brief should say 'this idea has to work'.
If you're an interior designer and your brief is to lighten a client's front room, you may well suggest painting the walls white, thus reflecting light around the room.
The client may well 'feedback' they don't like white. The interior designer may not like white. But the trained, experienced professional knows white works as a solution to a problem and recommends it.
If you want your marketing to be effective, whether it works for the customer is far more important than whether either party like it or not.