Peter Mandelson's return is a Good Thing.
First, he is an exceptionally good departmental head in a government where there are too few. Although I look forward to a Tory victory at the next general election, it would not be a bad idea to have a few departments functioning until then.
Second, he was a genuine and well-informed grasp of the importance of international free trade and the global economy. This was demonstrable at the European Commission. To have such a person in the Cabinet would be an asset in any government, Tory or New Labour.
Third and last, he is a political counterweight to a domineering Prime Minister. This may in turn lead to more broadly-based decision making. Again, this would be useful while we put up with this (generally-speaking) shambles of a government in the meantime.
However, the main cost of this appointment is the weakening of the UK's position in Brussels and a possible dilution of the EU's free trade stance.
A weaker European Commission is usually also a Good Thing, though perhaps not in this one policy area.
To be both missed and welcome is an unexpected development in Mandelson's career. I am surprised to feel both.