From experience, I find that improvising on a really powerful theme is very difficult for a number of reasons. What do you do to have your improvisation say something of its own when the motif is universally overwhelming and constantly drawing attention to itself ?...Maybe you could take small fragments of the melody and expand them rhythmically, change the key, plop in peculiar harmonies, things like that ?
In short, I like it Andrew, keep working on it, don't hurry the process and be yourself, not Liszt and the rest; they've had their turn, they're dead, it's your turn now. Keep returning to it. You are very good at transcriptions and paraphrases, it seems to be your natural mode, in the same way as our friend quantum is so good at impressionism. Bit less pedal perhaps ? I hate looking for blemishes, it's not in my nature, but the tune itself is very crisp, sensually flirtatious, is it not ? Or am I merely remembering the Hollywood version with Dorothy Dandridge ?