mmm i just heard someone mention it has a SO HARD piece, but heard several people think it is an easier etude, so well what is it for you?
It really depends HOW you want to play it. It is not a big deal to learn it and just play up to the 144 tempo. But the nightmare starts when you want it up to the tempo and sound like a breeze, when ALL the chords are PERFECTLY voiced, and all notes in the melody are PERFECTLY even. And it should be... musical.
The next problem starts when you CAN do it and deside you want all of these but already at 152, and so forth.
The next problem starts when you finally get confident and brave enough to deside to play it in public. Depending on how critical you are to yourself, the first attempts might dissappoint you, as on stage, unlike at home or in class (where you feel relaxed and comfortable) things start slipping. So you start all the work over again, keeping in mind what chance you take.
It is one of the very few pieces that will be chasing you all your life like a nightmare.
The best 10/2 live I ever heard was from Tchaikowsky Competition, with Vladimir Ovchinnikov. It was PERFECT. Very quiet, no single note was out of melodic line, no single note in chords dissappeared or was sticking; it was very fast and still musical. He worked on it an hour every day for 5 years. This time sounds about right to invest for anybody who wants to play this etude in public well, if not perfect.
And if somebody tells you otherwise it means two things:
1) The standards of the person are not high enough, or
2) It is just out of ignorance.
Oh, and BTW, as Chromaticler has already rightly mentioned, the 4-5 finger technique learnt in La Campanella has nothing to do with 10/2. Not even close.