Just a few quibbles on the series
-a few arcs were a bit long in the tooth
-I don't quite care for the strong emphasis on fighting. They're done quite well regardless with the uniqueness of Devil Fruit powers eventally drawing me in, but I'm much more interested in the adventuring and fun-loving aspect of the series.
-Old favorites like Buggy and Smoker haven't returned since Skypeia
-Nami's, er, 'developed' proportions. I liked her better when she was more Luffy's age.
-Some scenes depicting the victimization of Robin and Nami in recent arcs. While their captors eventually got their just desserts. Robin's abuse seemed too brutal for too long, and Nami getting assaulted and being at the mercy of Absolom just made me feel dirty. I'd prefer if she did more during that arc that become a sex object. Thankfully, some of the more lighthearted moments of the latter, such as his inability to kiss her during the wedding cerimony, as well as a good assertion of her independence in parts helped it become more tolerable.
Other than that, I have a lot of love for the series and it's characters. I don't think I could dislike the series for becoming too goofy since that's what I grew to like about it.