Assuming this is true, I don't even know what to think at this point.
On one hand, the DCEU has arguably been one screwup after another. MoS was average, and both BvS and SS were both highly divisive, and I wouldn't be fazed if WW and JL are misfires too. So if the script for the Batfleck is trash, that wouldn't be too shocking.
On the other hand, WB management is arguably in complete shambles by this point; for all of the alleged complaints about the script that have been made, the studio execs involved probably couldn't pick a script with potential if it sprouted wings and hit them right in the jaw. Especially if the reports about them being only in it for the money aren't without merit.
And personally speaking, Batfleck and his scenes in BvS were the only bright spots I enjoyed in what was otherwise one of the most incoherent films from a major studio I've ever seen. (Also a fan of Affleck's Argo as well.)
I want to have faith that Affleck can put out a damn good take on Batman with his film, but I wouldn't be surprised --though disappointed all the same-- if it too fell into the same hole the DCEU as a whole has driven itself into.