Xamarin.Forms does not come with a graphical designer (yet ?). As for intellisense there are 2 parts:
- referencing xaml element tagged with x:Name in code behind works in both Xamarin.Studio and VisualStudio
- Xaml completion of elements and attributes works in Xamarin.Studio, and support for completing attributes values is coming very soon. Unfortunately, intellisense for Xaml in VisualStudio does not work for now. But the problem is well known, and solutions are investigated.