My constructor's spidey sense tingles when I see huge open white spaces like these. Gigantic chunks, roughly 7x7, can't consistently be filled with entries that are both sparkly and smooth. I girded myself for a solving experience filled with made-up sounding -ER, -EST, RE- words, plus a bunch of esotery.

What an immensely pleasant surprise in the NE corner, then! There isn't anything that shines except IRON MAN (I love me my superheroes), but so many of those seven-letter entries are fine. PIRATES and ARACHNE are nice, THISTLE, BATTLES, and CONCISE too.
Okay, the PACA is iffy, but it is a real animal, so I can let that one slide. ENSURER was the only real sticking point for me — I plunked in INSURER, sure that it was correct. But with just a single made-up-feeling entry, this corner was a standout, as compared to other wide-open puzzles.
The SE demonstrates the typical trade-off constructors must make with these types of big corners. It's so smooth, only PRIE needed as crossword glue to hold it together. But nothing much stands out to me. And it does feel heavy with names that can't take clever clues. Yes, RODRIGO Duterte is (unfortunately) crossworthy, but you're never going to have a playful clue for him. Similar issue for Robert Cavelier de LA SALLE and PETULA Clark.
The SW suffered the most, I thought. It had the most snazzy stuff — I love TIM RICE's lyrics, and BAD DEBT and WEENIE are great entries that could have taken imaginative clues — but RAMADAS (open-sided shelters?) felt 1.) esoteric and 2.) like a constructor's crutch, what with that friendly vowel-consonant alternation.
Oh, and UNALERT … oof. It does appear in some dictionaries, I guess. Along with the ARECIBO / TIM RICE crossing, which is probably unfair to many solvers ... double oof.
Along with the lack of interlock — notice how all too easy it is to describe the puzzle in terms of four quadrants — this isn't my favorite style of themeless. Still, it did provide a good Saturday workout, and the change of pace every once in a while is welcome. And that top right corner turned out well for this type of puzzle!