It makes Quicktime work at least as well with WMV files as VLC. The browser plugin works at least as well and in some cases better than the WMP version. It doesn't support any more capabilities that the WMP for Mac app did so any files that were WM files made with some crazy extra codec like DivX or something still probably won't work. But it is a suitable replacement for WMP and, at least, we can look forward to this product being updated at some point in the future. I have had no problems whatsoever with crashing. I had some issues getting an mms stream to play in Firefox (worked fine in Safari) but that worked fine after I logged out and logged back in (even though the installer didn't tell me I needed to. The only issue is that the Quicktime progress bar and controls don't fill the same amount of space on a page as WMP so it doesn't look quite right but it works. Now if only they'd make a RealPlayer plugin.