Fe (theoretically) seems like a burden to me sometimes. even though it's easy and essentially second nature in real life, theoretically, i don't wanna have to come up with an answer to a compliment... 0_x;
oh, but to the OP. i like (genuinely) complimenting INFPs and watching them squirm and blush.
the couple of ISFPs i know, i've never noticed them getting very squirmy.