For me personally, Rust was a challenge. Most programming languages are more or less the same. But Rust forced me to think in a way I've never encountered before. I guess this is also why many people like it.
For me, I wouldn't say it's just because it was a challenge. The ideas that Rust makes explicit — borrowing, tracking lifetimes, mutable vs. immutable references — they're lessons that carry over into other languages very well.
