Mixed bag for me. +A threat to Dragons, although that makes Ice-types even more useless, being displaced as Dragon-slayers by a type that hits them slightly softer (x2 vs x4 SE) and are an easy switch-in. +Poison more viable offensively (if the rest of the rumours are true). -SEness against Dark (if the rest of the rumours are true) is unnecessary, and makes a load of frail (most Gen III and IV) Dark-types even less usable, with Tyranitar left as *the* Dark-type to use, even that mostly due to its stats and ability. -Flavourwise, I'm still unsure what Fairy encompasses exactly, such that Gardevoir, Jigglypuff, Sylveon and Marill are all Fairies, and one Fairy-type move involves the Moon. Are Pikachu / Lunatone / Cresselia / Moonlight, etc. all to be retyped or left confusingly as they are?
Well, I was liking the idea of a balancing type before it was revealed. I thought that it wouldn't be named fairy type and hoped that few old pokemon would be fairy. Unfortunately, Gardevoir is now part fairy with new weakness and thus, I HATE it.
I loathe Gen V. I am being optimistic for Gen VI, because I hope they can make a good new feature.