What is your reaction to Junot Díaz’s “How to Date a Browngirl, Blackgirl, Whitegirl, or Halfie”? Did you enjoy reading the story?

The question is ultimately an opinion question.  As long as you state your opinion and clearly defend why you think what you think, then you are good to go.  
I remember reading this story the first time, and my response was typical of what I see from my students when I have them read this story.  Our initial response is a blend of shock and disgust because of the narrator's unflinchingly blunt description of his tactics to have a girl over and hope for sex.

 If she's a white girl, you know you'll at least get a hand job.  

What's clear at the beginning of the story is that the narrator believes that he has to hide his ethnic background and poverty in order to have the best chances with a girl.  That's why he opens the story with narration about needing to hide the "government cheese."  As the story continues, readers come to see that the narrator also believes that he has to act a certain way in order to impress a girl of a certain race.  The narrator is a chameleon that is willing to transform himself for possible romantic activities.  

Tell her that you love her hair, that you love her skin, her lips, because, in truth, you love them more than you love your own.
She'll say, I like Spanish guys, and even though you've never been to Spain, say, I like you. You'll sound smooth.

The narrative is also offensive because it simply doesn't ever emphasize the fact that girls, of all races, are individual people with their own likes and dislikes.  The narrator simply describes that all girls of one race like things a certain way, and all girls of another race like something different.  That kind of blanket stereotype is crazy.  
To answer the second part of the question, no I didn't like reading this story the first time through it.  I found the narrator's attitude about women offensive, and I thought he was a coward for not trying to "be himself."  Of course my attitude about this story has changed as I have become more familiar with the narrator.  I'm still offended by his thoughts and attitude regarding women and races, but I find his narration much funnier now.  Each time I read the story, I can't help but feel that the narrator is completely full of faked bravado.  He sounds like he knows what he is talking about, but I now believe that the narrator is faking his confidence and pantomiming the actions that he has heard are supposed to work on girls.  

Don't panic. Say, Hey, no problem. Run a hand through your hair like the white boys do . . . 

It's like he's trying too hard to be cool, and that is why my feelings about this story have changed from my initial feelings.