I think there will definitely be a way to tone down the effects.
I love having everything on full, bits of spells flying all over the place and what not, just seems more fun!
in saying that I'm sure once we've been playing the game and we all know what spells look like what it won't start to look as much of a hectic mess like it does on some youtube videos. Let's face it, the youtube videos don't really do games justice.