So far I've had mostly mixed feelings about it - some things are done well, there are some nice character moments, and the animation is growing on me.
But after episode 5 I'm leaning toward a negative opinion. It feels like they are just changing things to be edgy and they don't really make sense. I don't see the point of the kid's story other than to make Vash look bad, and to have a big reveal with emotional impact, which feels unearned. The original story with Monev was fine, and it seems like they're just trying to make it edgier and more shocking.
Vash comes across as way more incompetent in this version, which deprives him of a lot of his nuance as a character. Vash's appeal is that he looks and acts like a dork, he's a ridiculous pacifist, he's been in love with a dead woman for over 100 years, but he can back up his wacky behavior and philosophy because he's just that freaking good. In this one, he's an idealistic dork that can't back it up; Vash loses a lot of his charm when he just takes L after L, doing nothing useful and being vaguely sad all the time. The character of Vash is one of the strongest and most unique aspects of the original Trigun, and so far, it's been diluted in this adaptation. It's like his entire frame as a character has been shifted and I'm not confident that there's a good reason for this.
A lot of stuff is really hamfisted too, like the opening with Roberto explaining to Meryl what a Plant is? Why wouldn't she know that? That's like explaining what computers are to an adult.
Overall my impression is leaning toward this is just another gritty reboot trying to milk nostsalgia for the original series, without the stuff people really liked.
Another thing is that it feels like more a mish-mash of other franchises rolled into one, instead of its own thing. This could be because "wild west, but in space" is played out, but I recognize heavy elements taken from Dune, Star Wars, Firefly, and a few other shows.
After all that, I still don't hate it and I'm trying to give it a chance because some stuff is done really well and it gives me hope. I fear that this is going to be another Star Trek: Picard though, where they shit all over an established franchise with a grimdark reboot that slanders as many beloved characters as possible.