Why Xamarien is not suitable on Mobile apps ?

 

Why Xamarien is not suitable on Mobile apps ?

1. Yes, it takes time, but usually around 1 month from first beta. So, for example, MonoTouch 5.99.x has been out for 2 months, which is the version that supports iOS6. I'd expect MonoTouch 6.0 to be out within 2-3 days of the iOS6 release - which is TODAY!

Other than that, yes you are right. You DO have to do the UI for each platform seperately, but you get a native app on each platform, not a mash up lowest-common-denominator. It IS more work than a Write Once Run Anywhere, but it's also a LOT less work than writing an ObjC (iOS), Java (Android) AND .NET (WP7/8) version seperatly. All the non-visual stuff can be shared.
 
The relatively newer APIs of the platform will take some time to percolate to Mono.

I can't say 100% for sure on Android, but certainly on iOS they've had day one support for new iOS versions and their new APIs since (I think) iOS 5.0.

On your other points, I'd add:

1.  Having to build a native UI isn't so much a drawback, since you'd have to do that with native development anyway.  Also, check out Xamarin 3.0 Forms - new API providing cross platform, write-once UI development across Android, iOS and WP8, released yesterday.  It's not going to solve everything in one hit, but it's certainly going to be useful productivity tool, particularly for enterprise apps.

Advantage & Dis Advantages Of Xamarin