BTW, I'm getting better at playing by ear: Twinkle twinkle... Mary had a Little Lamb, even Of the Father's Love Begotten, and parts of Concerning Hobbits. But I really have trouble reading the music and translating that to finger positions... That is going to hamper me in the long run, isn't it?
I'm not 2J, but I'll butt in anyway...
In my opinion, being able to play by ear is as important as being able to read music. They're both good skills to have. I've been really working on my ear training lately...my sister can go to a playing session, hear a song a couple of times, and be able to pick it up right then. On the other hand, she really struggles with reading music. She has to go very, very slowly, note-by-note, which means she usually waits for one of us to learn a tune from the music and then picks it up by ear.
I envy her to an extent, but I also like being able to take a piece of music I've never heard before and pull it off the page, make it real. It's a great experience!
Of course, if you already read music and are just translating this to whistle, I've said a bunch that I didn't need to say...oops...