I just finished it! But since it's 2 AM here, I'm going to post it later because I'll have to PrtSc all the pages, and I need some sleep!
I would say it's about the same difficulty level as Papa. However there is much more of a pattern to HaWBtW in the rythms, I think, than there is in Papa. If you can't play Papa, I can give you some tips on how to learn it.
First - Practice, Practice, Practice! Don't expect to learn it immediately because it takes time. I've practiced Papa for hours on end, and it was worth it. (Though I did end up with a lot of arm pains.)
Second - I know everyone says this, but it works, try playing it slowly. Also, try learning the parts for each hand separately, then together, then at full tempo. And try listening to the song on CD as you play it. It helps you stay on tempo and you can hear where Vanessa sings. (For me, singing can be kind of hard when the lyrics are in a different rythm than what I'm playing.)
Third - Find some friends who are great piano players. I know a lot of people who play the piano at my school, and they were nice enough to give me tips on how to play. I've been teaching myself how to play, so my technique was atrocious. I'm still working on it. Anyway, ask them if they can show you a good way to finger the notes. If you want, I can tell you how I finger the notes over AIM or something.
Also, I don't know how much musical background you have, but it also helps to be able to read music, and have a good ear. But I'm sure there are a lot of players more knowledgeable about these things than I am. If anyone else wants to give some advice, go right ahead! I'd love to hear more techniques.
Baronessa, your arrangement of Papa is fantastic! Thanks to you, I'll be playing it in a solo at my school's concert on Tuesday. Would it be alright if I make a full version of the song, using your arrangement for the opening part? I've figured out the rest, but I've yet to write it down.