Labour activists gave him a standing ovation, journalists write admiring of him, by all accounts he is a relatively effective minister - but the evidence suggests that far from being an asset, Peter Mandelson is a drag on Labour's popularity.
For example, he was ranked 'least trustworthy' amongst leading politicians in a survey by Populus, and would be a less popular choice as a leader of the Labour Party than either Miliband brother, Ed Balls or Harriet Harman.
I think the difference is this. In political and government circles, there is a lot of nostalgia for the golden days of Blairism - the message discipline, refoming 'centrist' policies, clear political leadership and good relations with the media. These qualities are admired by Labour activists, David Cameron's inner circle, civil servants and journalists - particularly compared to the chaotic governing style under Gordon Brown.
But for most ordinary people, Lord Mandelson symbolises spin and sleaze, and the policies that he champions such as privatising the Post Office and 'wise cuts' are unpopular with the majority. He is also a leading member of an unelected and arrogant political elite, as an EU Commissioner-turned-Lord.
It is often said that after the election Labour will face a dilemma about whether to follow the advice of people like Peter Mandelson and continue to be the New Labour party fighting for what experts call the 'centre ground' of British politics, or whether to listen to the activists and adopt more left-wing policies which will put off 'swing voters'.
But the example of Mandelson shows that the dilemma is in fact rather different. The qualities which insiders most admire about Peter Mandelson, and which they will be looking for in future leaders of the Labour Party are exactly the ones which repel ordinary voters. Although it goes against the Conventional Wisdom, the more that Peter Mandelson is seen to be the dominant force in the Labour Party, and the more control he has over our message and policies, the more we will put people off from supporting us.