First off, this episode had some of the ugliest Usopp art in the series. Art overall was not too bad, though the animation is weaker than the past few episodes.
As far as the episode itself, the filler content wasn't all that engaging up until Bartolomeo appeared and started attacking people with a pickaxe. Outside of having a cool power and a distinct design, Bill is quite bland. Kinda reminds me of Delvano Black trying to take on the world through sheer numbers (or rather helping Tesoro do it). Just not nearly as memorable.
Desire is a much more interesting character if only due to her past relationship with Bartolomeo and the unexplained fascination with chocolate bars. Essentially a biker chick that is somehow in the position to be a threat. Does she have a DF power, or is she merely savvy enough to realize that all you need to capture Luffy is with meat on a string?
Most surprising thing here is that this episode attempts to give Bartolomeo a backstory and history that is completely unknown outside of idolizing Luffy. One of those things that might conflict if Oda decides to give him a more involved backstory later on. Either that or it's canon and we won't realize it until years later.
Funniest thing, however, is that the Barto Crew and SHs are most likely not going to do squat in this arc until the end of it leaving Luffy and Barto as the only real stars. Very much in the mold of the Breed arc to that extent.
Otherwise this episode seemed like SatAM fluff. But I'm so starved for original anime OP material, I'll take it.
they put luffy and barto on seastone
As far as Barto is concerned, his hands are stuck together so he can't cross his fingers to create barriers.