It was pretty dragged out at times, but is was indeed a pretty great moment. Law hangs off Doflamingo longer than the manga, so I'm given the impression that Doflamingo's innards are little more than tapioca pudding by the time he finally stops. Another oddity is that Trebol is apparently more chicken given that he simply spends near half the episode sitting there watching Law attempt to murder Doflamingo.
But it was a pretty awesome moment to be sure, and the fighting that we got was pretty sweet too once Luffy finally decided to kick his ass. Technically, the episode was nothing outstanding except for a few moments, but it was fine.
Also, a user pointed out that Toei kinda screwed up the whole body double bit given that the double was shown as having the Heart Pirates tattoo on his chest as he was being shot by Doflamingo multiple times. The first (or should I say second?) bullet forces "Law" upward where the tattoo is clearly visible right before he is riddled with bullets, after the switcheroo was suppose to have taken place. That is unless Law's power allowed him to give his double the tattoo as well. I'm hoping this is fixed by the time the DVDs hit–looks like a pretty easy edit.
I also disapprove of where the episode cut, but I'm not too bothered by it.