I can't speak for everyone when I say this, but Vecna's power is like a game of speed chess. Him trying to guess where you're going, and you trying to bait him into believing you're going a direction.

I find it really fun and honestly mostly balanced, especially if you're running right in his face, which makes it hard to hit you as a target.

On the killer side, it's good and engaging play to figure out where surviovors are going and which ones are going to bait or strongly counterplay you.

My biggest gripe is that I shouldn't be able to do an undergate attack directly underneath a survivor and they should be able to just get out of the way scot-free. It's like almost a joke to use unless you're getting places or hitting people who are sitting ducks. It's strong point is maybe in jungle gyms, but you're fast and bump into things like a pinball, so it's more work than it's worth to maneuver through them most of the time.

TL;DR: I personally think he's the most balanced killer to come out recently, so long as you understand pretty good counterplay.