is virtual-repeat ready to be used?

I am trying to get virtual repeat to work. No errors but i can't get anything to actually display.
Is virtual repeat usable??
inside HTML there are elements there , but it is just not showing. Tried all the demos , reduced down to bare metal and still dosen't work. Give the same set of CSS as Demo and no.
I am on ember 1.0.14.
```
{{#paper-virtual-repeat model
class="vertical-demo" as |visibleItems|}}
{{#each visibleItems as |item|}}
{{item.message}}
{{/each}}
{{/paper-virtual-repeat}}

```