The pay-for-it version has some simpler standard notation.
I've got a similar app I'm workin' on.
It has lines marking off the measure/beat/subbeat so you can make out note durations a little better.
It's a good way to check your playing against a score.
(My app shows your notes on top of the score in piano roll format
- see the video page in link below)
Unfortunately, many good scores aren't available in midi format.
My little app just yesterday helped me figure out a tricky rhythm in Five For Fighting's "100 years" (the "lose yourself within a morning star" part)
I clicked in the notes, and used my "wait for me" mode until I truly "got" how
the rhythm worked in those 6 bars or so.
So these types of apps definitely help you when a piano teacher ain't there to.
(I only get a half hour a WEEK with my piano teacher - NOT ENOUGH time)
You definitely should get a teacher if you're serious, though.
I thought I was serious back when I got out of college and started my first job.
But it took me forEVERrrrr to learn a song on my own.
And there are things you just don't think to ask yourself when YOU're
the teacher.
So my advice is just get a teacher.
If you can't afford one, well, goof around all you want, but don't mislead
yourself into thinking you're serious about this (like i did).
15 years later, I get a teacher and have learned about 30x as many songs
in the last 2 years as I have in the previous 15

Piano playing is a sport. You have to do it every day.
And you need a coach to point out the dumb stuff you're doing.
(Because, obviously, if you're doing it, you don't think it's dumb)