Xamarin (opens in new tab)

I wrote a PoC (Proof of Concept) a few years ago of recompiling Xamarin iOS apps to Android without code changes and we released a few apps using that. It is especially handy for LoB (Line of Business) / internal apps which actually are very usable like this. Clients loved it as they only had to pay once. It has parts of the Core Graphics and Core Animation implemented as the last app I ported with it was heavy on those.

This was before Forms came along. No clue if anyone would be interested in it, but i'm cleaning up the code to put it on github as open source.

Since I'm just starting to learn it, does anyone have opinions or tips around Xamarin? Specifically I'm building a toy Android app to learn the stack, but I'm curious as to just how much reusability there really is between Android/iOS and other platforms.

While it does comply with title rules, I feel this could use a better title - have they just moved to Github, or did someone just find Xamarin interesting and decide to post their Github page?

How does Xamarin compare with other ways to get platform native across all platforms ? There's haxe (actionscript-like, but typed), which has lots of libraries. There's QT. I haven't even followed that well which others exist.

I started experimenting with Xamarin after they made it free with the open source announcement and I'm cautiously optimistic now. I can work around the works of Xamarin Studio (or the VS plugin) and I like C# and Swift about equally, but app startup time specifically seems subpar with Xamarin.

Edit: more on topic, the open source move is fantastic! I felt the money might be worth it for not only the tooling but also the top notch documentation, but I've never been able to convince any of my bosses on this.

Apps built with Xamarin (or a similar system where you bind to platform API's) or so much better to build and use than these cross platform platforms.