Free-quent Miles has an excellent analysis (Jan. 19, 2015) with math on the BA 2-for-1 awards available with the Chase BA card. In the past, I have both embraced and used, then later turned away from, these somewhat gimmicky awards.
Interesting. The analysis is sadly already dated, at least for post April 2015 redemptions with the major devaluation that hit the Avios program yesterday. Personally I think they are (or at least pre-devaluation as I'll need to rerun my numbers) an ok option for redemptions in F to Europe. I certainly wouldn't go out of my way to earn one of these but when I get one for MS I am doing anyway then it is an OK deal. As always run the numbers yourself.