I seem to have got a little confused.
Button brought out his contract with Williams in 2006, after the famous wranglings between him and williams over the previous few years. The CRB dispute was the result of him signing for Williams, whilst under contract to BAR, as a result of this, it would appear that he sacked his manager.
I am not sure about him paying a lot of money to stay with renault, my understanding was that he was loaned to Benneton/Renault by williams, who had the right to recall him in 2003, he was moved out of Renault to BAR when Flav wanted Alonso in the Renault.
From then, he stayed with Honda, possibly against other peoples advice and thoughts, although it turned out for the best, and I suppose you could not blame him for doing so with his history!
As for the subject in hand, I think that this is a good move for the team, and for Jenson. A bit of stability is good both from a driving and a team perspective. He has won races, and will win more. I also think that with what is potentially available to the team, I feel that he is about the best partner to Lewis.