I have been struggling with articles for quite a long time. Most of the times, I understand but then the more I understand them, the more it's getting perplexed!
For this particular question, I'm keeping in mind that the definite article 'the' is used for the one and only, a unique thing. Known to both - the listener and the speaker. If I say there was a table, it means there was some table but then if you and me are standing in a hall and we see a table, I won't use an indefinite article. There, it's Do you see the table? Quite clear.
Let's extend this further...
You and me are standing on a footpath. And we see a sexy Bentley...
"Wow, what a car!" is generally what we hear. But...
why not the? I'm talking about that Bentley only --that particular car, in front of us (like the table).
And to argue, I'm not talking about the same model by German Volkswagen AG (or else 'a car' is justified!) because it has a beautiful sticker of Spiderman on it. Volkswagen does not make it that way!
Same case with...
"What the beautiful pair of legs!" - She's right in front of me!
"What the movie it is! Awesome!" - Telling someone in the interval.
Though I'm asking this question, What a beautiful... and What a movie... seems correct.
Ah, I am trying to come up with What the [countable noun]... examples but finding it difficult. Is it that weird?