The cape really isn't that complicated. Hold Y to run and press B to take off. No need to keep pressing a button to fly upwards like in SMB3.

From there, your only options are to either keep pressing left or right in a rhythm (Whichever is the opposite direction you're moving) if you want to fly horizontally, up on the d-pad if you want to dive, down if you want to soar upwards, or keep B pressed in if you want to glide back down (Far simpler than constantly hitting a button to wag your tail to glide down like in SMB3).

It's no more complicated than SMB3. In fact, other than the extremely easy to learn technique for horizontal flight (Which is 100% optional in this game), the cape controls are easier and more sensible than SMB3's raccoon tail is to use, if you ask me.

I guess we'll have to agree to disagree.