Had some good moments, but also a lot of questionable writing.
Act 1 was really good. Good exposition and to the point.
Act 2 was too dragged out for the content that was actually in it (way too much Udon that didn't progress the story at all) and I really think the Oden flashback should've been the finale of act 2 and not being pushed to the beginning of act 3. This way act 2 would've ended on a dramatic note and the stage for the raid would've been set perfectly.
Act 3 (the raid) was a treat to anyone that wants action without having to think too much.
It was a horror to those that want consistent and logical storytelling though (at least in many instances).
Another problem was that the arc had already been so long at this point, that Oda forgot (or had to) skip a lot of plot points he actually built towards in act 1.
But this has been a constant problem of Oda post skip. Just look at Dressrosa or WCI. First 2/3 of the arc are really, really good and then the final 1/3 leaves a lot to be desired.
All in all - trying to be as objective as I can - I would give it a 7/10 or so.
It really still is a fun read if you don't think too much about it, hence the rather high rating.
If I had to judge storytelling alone, it would probably be a 5/10 or sth like that.