Yeah the bending has been pretty weak in this series, maybe it's from everyone starting to rely more on technology.
I remember how the creators talked about the bending being based on martial arts and some character's being of specific ones like Toph's bending being Mantis Style.
With this series we don't really get that much.
Eh, we still see it.
I'm no expert, so I can't name it exactly, but Lin and Su certainly have two VERY distinct styles of earth and metal bending. Lin's a cagefighter, Su's a dancer. Kuvira has her own style of earth/metal bending too. As do Bolin and the Twins. Then Ghazan was a lavabender. So there's that. Toph's style hasn't really changed.
The show's had exactly three major firebending characters (Mako, Zuko, Iroh and P'li, if you can even count the latter two, I guess Korra as well). So i don't know if there's a lot of room for distinction there. Zuko bends pretty much as he always has, Mako is just kind of a typical firebender (same as Bolin really).
Airbending I think you can see a distinct difference in style between Jinora, Opal, Zaheer and Tenzin... well and obviously with Meelo (the less said about that the better, I can't believe that's still a thing...).
Waterbending. Again, certainly different styles. Tonraq fights like a warrior He uses water like a tomahawk or an axe. Unalaq uses water as an extension of his body and moves in tandem with it. Desna and Eska have their own style certainly. Kind of difficult to put my finger on it, though. Ming Hua was obviously really different. Tarrloq and Amon... I can't remember now.
Certainly, though at least as far as distinction, I think there is a lot of room to see how different benders bend. It's just there's less of them, there's less opportunities for them to show off, and we're dealing with a humongous cast. I think certainly in season 1 it could easily be said that in terms of scope, the bending was less impressive.
Every single firebender seemed incapable of throwing a ball of fire. (Seriously, in season 1 most of the firebenders just punch and kick with fire on their limbs, it's kinda lame). The Earthbenders moved the earth really slowly and purposefully whereas in Last Airbender you'd see a lot more dynamic earth movement, and earthbending was much more aggressive. Waterbending we just didn't really see much except in pro-bending (which is intentionally very restrained and tactical).
In season 2 that changed majorly, though. Unalaq, Tonraq, Desna, Eska, all were incredibly skilled benders with large scale water-based attacks. Season 3 introduced us to the Red Lotus, who were all INCREDIBLY powerful benders. And gave Kya and Tenzin a good showing in their fights. The sort of earth bending style of 'throw up a wall, hide behind it' was retired and we got to see the whole Beifong family in action.
I think overall the bending in Korra's been pretty impressive, it's just we've never gotten to see a really strong firebender in action. Fire is used by Korra, but most just intermittently with air and water used as projectiles. The closest was Iroh's battle with those fighter pilots in season 1, which legitimately was pretty impressive, but Iroh's been such a nothing fanservice character it's really been hard to be invested even in his few brief appearances.