So I've checked out everything I can find and I narrowed it down to two products/environments.
Available for a nominal monthly fee. I like the pricing. Makes sense for me.
It's also clear that it's early days for this product and some bits and pieces are still missing. I picked this up from blogs and their forums where people were asking for pretty basic stuff and running into problems that seem really common.
No thanks, for now.
Xamarin has been around a while and they are completely focused on platform independent development. Those two things give me confidence that this is a mature platform and that's important.
Xamarin allows me to write in C# and then neatly divides the various products into portable class libraries (which Xamarin makes certain works on all platforms) and then platform specific libraries for anything that isn't portable. This is a pretty clever adaptation and up to this point, working through the examples, the stuff has actually worked.
I've also noticed there is a lot of actual sample code that works and seemingly lots of support in their forums and online. That's really encouraging as it suggests the product is being used to create things that are used in production environments.
The drawback is the fee: $999 a year and I have to buy a Mac computer for another $1,000 if I want to deploy stuff for iOS. Ouch.
So Xamarin it is. Now let's try to get this sucker to authenticate against a selection of Identity Providers (Facebook, Google, etc.).
It doesn't hurt that Microsoft has just purchased Xamarin.