This. My younger sister is like 3 worlds ahead of me, and she won't stop rubbing it in. =.=
I've been exploring a lot, grinding, taking things slow, also she's on beginner, and I'm on proud. =/
Well, beating on
Proud sounds a lot more impressive than beating on
Beginner. Proud, you can be proud of the accomplishment of beating all the hard bosses, etc. Beginner...not so much. (I mean, congrats on beating the game, but it probably wasn't much of a challenge doing it, and challenges are what makes games fun

Plus, you can get a secret ending. And it's still unknown, at least to me, how to unlock the secret ending in Beginner Mode. But if your sister figures that out, then I must say that is an amazing feat., seeing as how no one else discovered it as of yet)
I tend to take my time as well. Not sure if it's cause I'm on Proud or because I enjoy trying to unravel every part of the game (I've been so focused on unlocking a lot of nice and powerful commands/abilities from my DE's lately)