From what I've played of the ingame stuff, yeah I like the campagin so far in temtem more in Sword and Shield, there's an actual difficulty there!
Hard to say on the competitive side though, as I don't quite have a handle on it yet. However, I think the breeding mechanics sound worse, and the current way to "EV train" (called TVs in this game) is really awful and grindy. Granted, competitive Pokemon is my main concern, and I realize I'm a pretty niche part of that audience.
Still, Temtem has a lot of potential, I like what I've played thus far!