I made a quick side by side comparison between Fira and Meta Pro: http://i.imgur.com/Oo3yeYx.png
I made a quick side by side comparison between Fira and Meta Pro: http://i.imgur.com/Oo3yeYx.png
Having an OFL (Open Font License) font of high quality is a good thing.
Also OFL licensed is Andika (http://scripts.sil.org/andika) which I'm using in an app for children as the letters are mostly in the form that they would be handwritten was the best I could find in a few hours searching (free and paid) and most of the licenses for use in apps looked very expensive.
Also, I like Andika. To me, it looks like a proportional-width interpretation of Monaco, a monospaced font that has shipped with Macs for the last few decades.
In this case, Spiekermann made both fonts.
As you can see, all the areas in which Monotype Arial is different from Linotype Helvetica are borrowed from Monotype Grot. The reason to make such a monster is purely financial.