I would simply ask the person what it was he or she didn’t like about it. If you get a specific answer, then it’s not a bad idea to ponder whether that person has a point or not and then try to improve your playing. If they won’t give you anything more specific, then I wouldn’t worry about it. No matter how well you play, you will never please everyone, nor do you need to. That’s just the way it goes.
If everyone liked the same things and played the same way, there wouldn’t be any need for more than one recording of each piece. Music would get quite boring quite fast.

Also, don’t forget that this type of non-specific critique from a peer (especially if you didn’t ask for their opinion) might just be envy on the part of the person giving it. Just nod, smile, and forget about it.

How would you deal with a criticism from a peer such as, ‘I didn’t like it’, not being specific. I seem to deal with any type of criticism except this type. Is there something I should say or a particular way I should think about it?

Cheers