That's awesome, how did you manage to figure out which notes would work well together? If you've been playing piano for a while, but haven't taken lessons, chances are you actually know more music theory than you realize. I was working under the assumption you were still at a pretty basic level. How long have you been playing the piano for? It's a beautiful piece, but if you're unfamiliar with the piano, you might find it difficult. Even though there's a lot of repetition, if your fingers aren't dexterous it'll definitely be a challenge. One of the first pieces I learned was this one. If you can already play a few pieces at that level, you could try moving on to something that takes more co-ordination. When I was trying to build up some finger dexterity, I moved on to this one and the odd reel or slip jig. If you've already got some experience with songs at that kind of level, then I don't see why you can't give Fringe a go. It sounds challenging, but if you like the song it's huge motivation.
I'm very curious about these things, I just paid attention to what sounds good to me and what doesn't and found the differences. Songs I like tend to have evolving patterns, challanging me to guess what comes next so I can feel clever when I do, each time the notes or rhythm change, they change based off some 'rule' so I can predict what's going to happen with some difficulty. Sometimes the rule changes too, and there are rules about rule changing etc. No idea why I still like some songs I've heard a million times though, I'm guessing there are several elements to music that people enjoy. how did you manage to figure out which notes would work well together?