Nothing new, in short. Just another of your average mage champ, no new mechanics, nothing. Pretty boring.
Honestly, I think the people at Riot need more creativity, their champs' mechanics are pretty limited, every now and then there's an interesting champ, but the rest are really similar to each other, in the sense that if you can play one, picking up another isn't that hard.
DOTA is so much better in terms of variety of mechanics. A large portion of its champions have unique abilities that can seperate their playstyles completely from the rest.
If you take the two newest champions from DoTA for example, Kaolin and Nerif, they have really interesting abilities and mechanics that I bet an average LoL player probably will have no idea how to use at first. Kaolin has his rocks which require thoughtful positioning. He has rolling, pushing, pulling, silence, slow and a very interesting ultimate that can make his rocks explode. I can think of all the possibilities of ridiculous outplays that this champion can put out, but I would imagine them to be really hard to pull off. And Nerif, he's really interesting as well, a skill that blocks all spells but enhances damages from other sources ? A skill that damages but then after that heal ? A spell that delays all damages and heal ? If those abilities aren't interesting, I don't know what are.
But Vel'Koz, what does he have ? 2 skillshots that deals damage and slow, 1 cho'gath skill (-1 for uniqueness) and 1 laser gun. That's it. Another damage dealing champ, nothing more nothing less, he's not gonna provide anything different to the game, and can be easily replaced by another champ. Yasuo was fairly interesting with his wind wall, his dash and his knock up ultimate, but Jinx and Lucian are just your average champs providing nothing new.
EDIT 1:
- All I am saying is that Riot could do better with their ideas. If you want to take it defensively, bah... If you want to keep the game simple, I guess that's fine too.
- Kaolin's unique point is his rocks. Having something else that your abilities can interact with is pretty rare. By that virtue, Syndra's also interesting as well. I did say that "every now and then there's an interesting champ", I am not saying that all LoL champs are boring. I am saying a lot of them are.
- Narif - I am saying he's interesting. Abilities that are double-edged are something pretty neat, it adds another layer of decision making. I am not debating whether his skills are better than comparable skills.
- If you take some of the people's ideas here or Riot's forum, they have pretty amazing stuffs that have never appeared in any other game (if you want an example, the helmet bro guy, he's got some pretty neat mechanics). So it's not like all avenues have been explored.
- The thing about Vel'Koz is it's not that difficult to figure out how he's gonna be played. Land your skillshots. That's pretty much it. The learning curve isn't that steep if you have played other skillshot based champs.