Don't do it in the interview!
1. Asking that sort of question on the spot will most likely convey lack on self-confidence.
You are supposed to be knowledgeable and self-possessed in an interview. Asking for that sort of feedback will come across as asking for validation, or reinforcement, when you're the one who is supposed to be convincing them that you're the best, not the other way around!
2. You're putting them on the spot.
They might think your CV is pretty poorly formatted, or not at all what they are looking for (you did make it into the room, but sometimes HR forwards resumes that the hiring manager may not like, etc). But they most likely won't tell you that to your face. Very few people are comfortable openly criticizing others, because it's seen as unprofessional in the workplace. Instead, they will probably offer you platitudes: "Oh yes, it's a very nice resume", or "It gets all the information across very succinctly", which may not be what they're actually thinking.
It is customary to write a thank you e-mail shortly after the interview. Send that out with a short request for feedback:
Thank you very much for taking the time to speak to me today. I am very excited about the prospect of joining you team, bla bla bla. As I'm always looking for ways in which I might improve myself, I would like to ask for your feedback regarding my resume and my presentation in the interview. Any critique would be greatly appreciated.
This gives the person in question time to gather their thoughts and compose a message that they are comfortable sending you, instead of blurting out a platitude simply to avoid an awkward situation. At the same time, people will tend to be more honest in a written communication, than face to face. Quite simply, if you're not taking their advice well, they are not in the room having to deal with your reaction.
That's my advice, at any rate.