This is great! It will take practice -- but not because there are any moves or sleights -- just a technique that needs to be done naturally and casually. This is a very clever technique and the effect is a true "worker".

If you are the spectator, there is only ONE explanation other than the premise you have an amazing memory -- which is why you really must use a borrowed deck. Using a borrowed deck eliminates any possibility of that one explanation, leaving the spectator gobsmacked at your supernatural ability to memorize a shuffled deck in seconds so that you can instantly identify their chosen card.

I really love this kind of effects.
This one particularly because the spectator does almost everything and there is no manipulation of the deck.
Impromptu and direct.
Every step is justified.
Fooling and intriguing.
Highly recommended.