This sounds like good news. I felt that Fiat were only attempting to buy in to boost their own ego so could only see a world of pain if they succeeded in their bid. Magna may not be a car manufacturer themselves but are heavily in the automotive industry so means they are well placed to know how to run Vauxhall/Opel. And hopefully with the GM stake it may well mean that Ellesmere Port will get the Ampera which I believe is an extremely important cat not only for GM, but for the future of the automobile.
The one worry on this is the "contribution" of our government. The German government may well put up 1.5 billion euros of bridging loans to assist the transition. As far as I know the UK is not chipping in. This may well be remembered by Magna...