It was bad to me. Some might like it but I didn't.
Of course my main problems with it were...how much actually got accomplished in the arc that contributed to the story? Robin read the bell thing and got some info on Roger and that weapon...they got some gold...and Usopp got more toys for his arsenal.
I can't think of anything else that actually got done that contributed to the story. Maybe if the arc had the crew interacting with Robin and getting used to her it might have helped? Maybe if Enel was more of a important character within the actual world of One Piece it might have helped? Whatever the case, I don't feel like it accomplished much and the flashback miniarc made me want to throw my computer. We spent several chapters exploring about characters that we already dead and had no real impact. This annoyed the shit out of me.
But there were things I like. Enel was entertaining, I think Gan Fall was cool, and I did like the design of the country...to an extent. But Water 7 needed one chapter to completely show it up so now I hate it more.
But that was just my two cents. Some might like it, I did not. Weakest arc in One Piece so far in my opinion. Maybe it will change when I get to this Hodi guy? 😛