Back in May there were many reports of Virgin customers finding the Spotify service unusable over VM broadband, including me (see this post: Spotify problem fixed - oh no it isn't).
Well, I've been using it all day and I'm pleased to report I've had no stuttering whatsoever, so it looks like it may be fixed. Still not convinced I will pay for the service when my free year ends, but at least it's working properly again.
(Incidentally, there's a quick workaround you can use if you have stuttering service on an iPhone: make the playlist available for offline listening. Be sure to select the Extreme quality setting to get the best sound.)
UPDATE, JULY 15TH: Not fixed. VM reckon I have an issue with my signal strength again. Will leave it until after my upcoming holiday before booking any engineer. Anyone else having issues still?