You put me on the spot, xvimbl, and I'm already regretting my obiter remark on the musicality of Liebestraume, which was, as I said, a first impression, not a considered judgment.
Still, I'll try to rise to your challenge as best I can, if that's to be the price of getting an answer to my actual query.
While longer acquaintance may reveal emotional subtleties that aren't apparent to me now, it seems to me to be pretty straightforward expressively.
The piece as a whole is marked "con affetto", by which Liszt certainly intends not only "with feeling", but also, and more to the point, "with affection", or "with tenderness". At the risk of making it sound more programmatic than it is, I would say that the piece begins with a mood of warm tenderness appropriate between a pair of lovers (dolce cantando), passion is aroused between them (poco crescendo ed agitato), pausing for breath in the first cadenza, only to return yet more forcefully (piu animato con passione) following it. The passion grows continuously (sempre stringendo, sempre piu rinforzando, etc.) to its almost painfully postponed fortississimo climax, followed by the delicious detumescence of the second cadenza. Finally, we return to the tempo primo as the lovers, their passion gratified, relax into slightly playful (I'm thinking of the left-hand chords in the treble) calm sweet harmony (dolce armonioso). I won't say they drift off to sleep in the final bars, because this description is already more literal and programmatic than I'm prepared to stand by.
Anyway, that, very briefly, is prettty much what I think the piece expresses, and if there are hidden depths I'm not aware of, I guess I'm just too shallow to see them. I'm always prepared to learn, however; and I have, as I say, only just begun to learn the piece. It would be wonderful to learn something from it about the human heart, and not just about piano technique.
But all this is by the by. My original question is still what concerns me at the moment: does anyone have suggestions for practicing the technical difficulties the work presents?