Unpopular Opinion: Elementalist Lux doesn't fit the character
I've always seen Lux as everyone's lovable, cheerful, upbeat and happy-go-lucky light mage that never hesitates to remind us to stay positive and focus on the game. Her tone of voice is always slightly giddy and she never sounds too serious.
Elementalist Lux is a great skin, don't get me wrong. Riot did an absolutely superb job working on it and it's definitely the best skin to come out yet. However, nothing about the skin screams "Lux" to me. She looks like a different character entirely, especially her face in the character icons which when compared with her original splash look like someone else entirely. It's actually somewhat difficult to identify her as Lux at first glance. I know ultimate skins are supposed to be a total overhaul of the character, but you can look at all the other ultimate skins and immediately tell what character they're for; the same can't necessarily be said about Lux. The only obvious clue that it's supposed to be Lux is the staff, an item that several other characters also have and isn't necessarily unique to Lux.
My biggest problem though is that her voice lines just don't really sound like Lux to me. She went from being upbeat, positive and carefree to being some edgy punmaster who's always biting at the bit to crack her next joke. Even though it's the same voice actor, that spirit from the original just isn't there.
Basically, I think Elementalist Lux is a fantastic skin; just not a good LUX skin. I know most people probably disagree with me, but I'm still probably going to end up swapping between this and my other Lux skins I already have, because her original persona is a big part of what draws me to her as a character, and it's something that's sadly missing from her new skin.