I'm thrilled with it! I've been using it for a long time and it's great. I've not used the HD features, as no one has ever asked me for WMV HD files. But I do know that WMV HD files are not supposed to play on a Mac at all, so you can make them, but still need a PC to play them back, unless that's changed.
You do need to be somewhat familiar with WMV settings, though. I learned by trial and error. I'm super happy with it. Great image quality, good sound. I only use it when I have to, I don't like going out to WMV files for my own use. But that's my gripe with WMV and Micorsoft, not with F4M.
Managed to get some decent files out in the end (I've used the free Windows WMV encoder earlier and were very happy with that - just too much of a hazzle and it doesn't take dvcproHD content...)
Payed itself back a couple of times on its first gig, when it finally worked.
I'll have to play around with it for a while, though to be really happy.
I've been very happy with it and get great results. I usually export from FCP quicktime conversion H264 to the specs I like and make the WMV file from that. Clients love it!