My V+ picture quality is great on all channels so problem must be specific to certain areas (I'm in Letchworth/Hertfordshire) or certain boxes (I have a week old black VM badged box - I know it was new because I watched the engineer unpack it).
Apart from a few VOD hiccups, I'm more than happy with my VIP 'upgrade' - V+ box/old STB in another room/Sky Sports (already had movies)/10Mb broadband (had 4Mb before), and costing me less per month than before!!