I can't speak to the "is it any good" part, but (after a bit of research) I can share what I've found. I'll try to represent things as best as I understand, but I may have some finer details mixed up.
ntex is written by the same person that started actix-web, Nikolay Kim (fafhrd91 on GitHub). There was a bunch of drama a while back due to actix-web using (what many reasoned to be) avoidable unsafe code, which was later found to be buggy. Nikolay was pilloried online, resulting in him transferring leadership of actix-web to someone else. ntex is, as I understand it, essentially Nikolay picking back up on his ideals for what could have been actix-web, if people hadn't pushed him out of his own project.
How ntex compares to the pre-/post-leadership change of actix-web, I don't know.
Here are some jumping points if you want more of the backstory.
ntex was formed after a schism in actix-web (https://actix.rs) and Rust safety/unsafety, with ntex allowing more unsafe code for better performance.
ntex is at the top of the TechEmpower benchmarks and beats most other Rust frameworks, although those benchmarks are not apples-to-apples since each uses its own tricks to eek out more performance: https://www.techempower.com/benchmarks/#hw=ph&test=fortune&s...
ntex is written by the same person that started actix-web, Nikolay Kim (fafhrd91 on GitHub). There was a bunch of drama a while back due to actix-web using (what many reasoned to be) avoidable unsafe code, which was later found to be buggy. Nikolay was pilloried online, resulting in him transferring leadership of actix-web to someone else. ntex is, as I understand it, essentially Nikolay picking back up on his ideals for what could have been actix-web, if people hadn't pushed him out of his own project.
How ntex compares to the pre-/post-leadership change of actix-web, I don't know.
Here are some jumping points if you want more of the backstory.
https://www.theregister.com/2020/01/21/rust_actix_web_framew...
https://steveklabnik.com/writing/a-sad-day-for-rust
https://github.com/actix/actix-web/issues/1289
https://github.com/fafhrd91/actix-web-postmortem