The cake is a lie.
Sorry, had to.
In all seriousness, for the most part, White wasn't much of a challenge to me. I had very few Game Overs (if I lose, I typically reset to give myself that feel) and most of them were against Ghestis. He really was difficult to beat. Nobody else in the game was. Many of the gym leaders were jokes and although I typically kept a consistent team, they really didn't have much of a problem with anyone.
I personally think that it was just as easy as any other Pokemon game, except playing through GSC for the first time. In my original Silver, I had a lot of trouble facing Bugsy's Scyther and Whitney's Miltank, but only because I was a newbie and didn't quite understand type advantages yet (and had started with Chikorita). I am replaying Crystal now. It's easy. Knowing those advantages and everything is what made Black and White seem too easy - GameFreak hasn't changed a thing, which sort of punishes those with knowledge. It doesn't press their boundaries and make them discover newness. It was the same game with different Pokemon. That is all it was.
BW was just as easy as all the others because they're all pretty much the same. GameFreak needs to give us something new, to tweak it (even in a minor way) every generation like Final Fantasy or Tales does with each and every game.