I was just thinking that a consistent vain here was that nearly everyone here has a gripe with their supervisor. They are either:
too demanding
do sweet fanny adams
have personality disorders

and they think that Ph.D's should be the way they were for them. They probably have pretty similar gripes about us (that's me just trying to be balanced and objective).

Although it may be the ultimate academic challenge for some, many very worthy students fall by the wayside, not because of luck but because of inadeqaute supervision. Should we not all have the opportunity to have a feedback meeting every year, where everyone is on an equal footing so that challenges can be addressed?

My university has annual thesis monitoring committes, where if there are problems with supervision a student has the opportunity to discuss these with other academics, and aim to have them resolved. Of course this depends on students being frank about any issues. Many wouldn't.

Most universities have the facility already if they have difficulties with their supervisor. Whether students choose to use them is up to them.

And this a forum where people come to sound off; majority of PhD students I've come across have got on well with their supervisors.

Ok this is probably going to be a bit unpopular but from a postdoc angle - I actually am beginning to think that some of the complaints aren't very fair on the supervisors and that 360 review might also actually be helpful in weeding out people who really shouldn't be doing a PhD before they've got too far in. While I was a PhD student I was very aware that several of my fellow PhD students were not very bright but very very deluded about their own abilities; now as a postdoc I'm hearing the real horror stories from the staff. One member of staff here for instance has just had to get a court order against an ex PhD student as she was stalking him and threatening his family after she failed her upgrade. The thing was despite the good qualifications she just couldn't manage PhD level work but just wouldn't accept that.
I'm beginning to think that it's next to impossible to tell at the application stage who will be a PhD suvccess story, as everyone has a 2:1 or better and good refs and that for fairness on all sides the review after a year's study, should really be used as a termination place for those that shouldn't be doing PhDs and to end problematic supervisory relationships for OK students that are already failing the student for one reason or another - it would be fairer on all concerned to do this early on, than letting it go further when the sunk costs make any dignified exit impossible on all sides.

Actually full-timers have these meetings twice a year at my uni. It's just part-timers like me who have them once a year. They're meant to check that (1) the student is making adequate progress; and (2) if there are any problems with the supervision. At one of my TMC meetings a supervisory problem that I wasn't aware of was identified starkly, and steps taken afterwards by departmental staff to fix things. So they can work well to fix problems, even when the student doesn't complain!