Mercedes GL 320/420 CDI Any good?

[Walter Sobchak]

Has anyone owned one of these?, I'm getting a bit fed up with my RRS and constant LR niggles, how does the GL stack up reliability and driving wise compared to an RR/RRS?, I was thinking about upgrading to a 2010 Facelift RR but really looking at the GL instead now.
Apart from reliability what are they like to drive?, economy,handling and comfort etc, my only other question, they seem to be kitted out pretty well-diff locks,low range,hill descent,airmatic, are they any good off the tarmac?, I know the newer ML isn't the best but these seem to come better equipped.