It's practically unusable when not in an environment with X11. I had to use it on a Windows system and any text would have incorrect letter-space. Every letter would bleed into the next, it's a typographic nightmare. You could use Arial Unicode MS to get a somewhat acceptable result but that won't support bold or italic text cleanly.

I'm not quite sure but I think the fix isn't even part in the 0.11 release. One has to compile wk himself to get it working.

When this issue is resolved this will be perfect, though. It has great capabilites to render footers and headers and JS-based output (in my case Highcharts). For the time being you can't even switch to commercial systems - ActivePDF, for one, has the same issue in the latest release.