"..According to what I read, the first movt doesn't quite make a satisfying sonata form movt and the last movt has problems 'because of its wealth of material'"...
I've played it, and I'd like to give some of my opinions on it. I don't think the last movement has a wealth of material, it's rather a long succession of ideas wich is then repeated in a different key. And then it all ends with a coda. In between he takes you through a multitude of modulations, where for example the main theme (the chordal opening) goes through, I don't remember, 5, 6 or 7 different keys all together.
Sonata form, well, he follows standard (Beethoven etc) formal procedures almost to the letter. Strangest is perhaps the development, which he almost repeats note-by-note, but in a different key; sort of a "double development" section.
The second movement is a real jewel! Play it!
The third has this odd section in the middle, I think he headlines it ad-lib or something. Bizarre, and quite fun.
The reason I played it is because I have a recording of Pollini doing it. Amazing! And I really loved practicing and then performing it. However, I haven't heard any other recording that makes me like it. Also, I've heard it twice in concert, once with Leif-Ove Andsnes. And it was horrible!:) So, I've since started doubting that it really is a successful piece, at least in concert.
Whatever, I think it must be at least thought of as a problematic piece. It's written quite 'thick', and sometimes you can feel that Schumann seems a bit lost. Even when he isn't lost, you have to work very hard to bring out the musical contents. I mean, even harder than usual! It has a LOT of notes! Very difficult chordal stuff, like the "da-da-da--da-da-da--da-da-da-da" in mvt1 (know which one I mean?) which easily breaks your hands when you try to make it sound right!
Listening to Pollini, though, it all makes perfect sense. Not a single musical line is blurred. But that is ....difficult!
Memorywise, perhaps the last mvt is the greatest challenge, partly because of the very many keychanges.