Forms & UWP - how ready is it? Custom Renderer examples available?

I've been using forms with Android and IOS and have been pretty successful so far. I'm starting a new app that also requires UWP.
I've put together a sample app with simple buttons in a grid. I've used styles in the App.xaml :

`

  <Style x:Key="ButtonStyle" TargetType="Button">
    <Setter Property="FontSize" Value="Large"/>
    <Setter Property="HorizontalOptions" Value="FillAndExpand"/>
    <Setter Property="VerticalOptions" Value="FillAndExpand"/>
    <Setter Property="TextColor" Value="White"/>
    <Setter Property="BorderColor" Value="#545454"/>
    <Setter Property="BackgroundColor" Value="#545454"/>
    <Setter Property="BorderRadius" Value="10"/>
    <Setter Property="BorderWidth" Value="5"/>
    <Style.Triggers>
      <Trigger Property="IsEnabled" Value="False" TargetType="Button">
        <Setter Property="BackgroundColor" Value="#5513007a"/>
      </Trigger>
    </Style.Triggers>
  </Style>
  <Style x:Key="LabelLargeBoldStyle" TargetType="Label">
    <Setter Property="TextColor" Value="White"/>
    <Setter Property="FontSize" Value="Large"/>
    <Setter Property="HorizontalOptions" Value="FillAndExpand"/>
    <Setter Property="VerticalOptions" Value="FillAndExpand"/>
  </Style>
</ResourceDictionary>`

One thing that doesn't work on UWP is the rounded buttons. It this a bug or just not supported?
Also - if I want change the look and feel of controls in need to use custom renderer. I've done this on IOS & Android, but I dont know where to start on UWP, are there Custom Renderer examples available?

Overall how ready is Forms for UWP?

Thanks!