I did not see that one coming, so score one more for the revealer style puzzle. The theme is so impressive, it helps me almost overlook all the crosswordese in the fill.
Look at all that theme! Two 14-letter and one 15-letter answer, along with the initial 10-letter, and the bonus MIDDLENAME of everybody's favorite transcendentalist, Ralph WALDO Emerson. Did you know he looked like this?
I have to say, I always pictured him with a large beard, a la Henry Wadsworth Longfellow. Or was it just that both of them are always referred to with their full name?
Anyway, the four theme answers are mostly strong. I could nitpick about the BARCELONAMETRO, which is a thing, but feels ad hoc in the puzzle. Otherwise, it's great to see the letter string NAME split across the two words of the phrases in each answer, twice split down the middle, once after the first letter and once before the last. Very neat.
So kudos for that. On the other hand, AQABA crossing QOM is some high level Middle Eastern naming that seems out of place in a Tuesday. That whole section, with plural name AVAS and random rhyme scheme ABAA is a good example of the level of crosswordese we have to put up with for the sake of the theme density.
DESC? I call foul on that one. Similarly on partial ABRA and IMA, OVO and OEN prefixes. My least favorite though comes at 53A: Clarinet need (ONEREED). Really? Is this to distinguish it from a double reed, a thing which nobody has ever felt the need to do? It's just a reed. You could call it a single reed. But not a one reed. Whatever that is.
On the other hand, ZIPDRIVE was fun, and an ANEMONE was an unexpected tentacled marine animal. Clever clues included 47D: What I may stand for? (IODINE) and even better 54A: Guess things (JEANS) with its hidden capital and lack of question mark.
1A: Plumbing problem (CLOG) gets a D- because I never like to hear from my daughters that their shower needs to be snaked again.