Has anyone been here? I read it is a difficult day hike. I'm curious.

I have not, but it looks awesome. I might have to put it on my list. It's warm and humid there right now, like much of Texas, and it's only going to get hotter as the summer rolls on.

EDIT: I was just reading more about it on Alltrails. Most people reported having confrontations with local land owners, but the river bed is 100% legal to hike in as long as you stay in it. If you do go, just be aware of this. I would always be friendly, of course, but would definitely know my rights before hand. https://tpwd.texas.gov/publications/nonp...igability.phtml

EDIT2: This is illuminating

I work in the South Central Texas heat. It is not ANYTHING to mess with. Plenty of water, hat, light colored and light weight clothing, more water, cant ever have enough water! Seriously...A LOT of water. I have learned no camping or hiking in July, August and at least halfway through September. My husband and daughter are very sensitive to the sun. I have to be careful of where I take them and for how long we are going to be out in the sun.
For those of you not used to the Texas heat and humidity, beware and be prepared. Plan accordingly. Lots of water and trail mix.
This caught my eye because my kids are grown (youngest will be 18 in a few months) and I would like to go explore some more. I also have some muscle problems, and would like to do these things before it gets worse. (they haven't figured out what the problem is so far) This hike is a maybe. So I am looking around and asking around.
I've read the article you linked to, thank you, and I also read the reviews on a couple apps and internet.
We will see! I am crossing my fingers, toes and eyeballs!

There are some decent to good videos about this hike on YT. On one of them, a local land owner commented. According to them, the traffic in just the last couple years has gone from a trickle of hikers to 20 or more in a single day, and this is causing ecological problems, killing, among other things, the otters.

I'm a bit ambivalent about this hike now. It looks like an amazing once in a lifetime experience, but on the other hand, I don't want to be part of the problem.

I understand the landowners concern. A lot of the rivers in the area have become crowded. A lot of new owners along the river banks as well. I moved here in 1993. The crowds and the population have just exploded. When I go to the rivers I go on a weekday after schools and colleges have restarted in the fall. If I go on a whim in the summer months, It is on a Monday morning.
As to why the otters are getting killed is a new one on me. That seems odd. Maybe the city slickers who are coming and scared of them? Or maybe just someone with a bad attitude? The ones with with the bad attitudes usually ruin it.

I doubt the landowner meant that the hikers were murdering otters, so much as making the place uninhabitable for them. When your habitat is destroyed, you die or else you can't reproduce, which soon amounts to the same thing.

Sounds like something similar to an area I loved to hike, the Red River Gorge in Kentucky. As word about it got out, it got loved to death: trails got trampled (widened and eroded), campsites became trashed, stamped down bare patches (usually far to close to the streams), and all the small trees near the campsites got obliterated by saws and machetes. Wildllife (deer and small animals) disappeared. Graffiti got scratched into the sandstone arches, and trash started appearing on the trails. (For some reason, an aluminum Coke (or Bud) can is light enough to carry in when it's full, but far to heavy for a mere human to carry out when it's empty.)

I hadn't hiked there in almost 10 years, so I went back for an overnight last fall, to see if things had gotten better (the Forest Service had closed some trails for a while, and moved the more popular trailheads back a mile or more.) Sadly, it was just as bad or worse - I ended up cutting the hike short after visiting one arch, and heading home the same day.

I hope the same overuse doesn't kill the Narrows, but I'm not hopeful.