I liked it but I think you are impressed more than you should be.
Regarding the blade breaking, it shouldnt have but it was a hype device.
Hakiless swords havent broken on Mr1, Kuma, Ryuma's Shusui, Mihawk's Yoru, Kaido's scales and so on and I am pretty sure that most of those things are tougher than Sanji's body and that Queen's sword is not that bad to shatter against Vinsmoke tech when nobody in WCI has shattered their weapon on Vinsmokes...
I like that he is getting PUs from Oda and he shouldnt stop there and should focus on the offensive part since all that he has gotten from exoskeleton was kinda already covered with raid suit. His defense is fine but far from amazing, the main problem about Sanjino is his offense, he is at the level of hakiless Chopper, cant deal any major damage to Queen. That's the part that I want to see Oda address about Sanji with next power-up.
Even though the exoskeleton can be considered as a replacement for Hardening, I doubt that alone is a massive AP boost over the regular invisible coating. However, he has now several things that he can stack on top of each other. Regular haki coating + raid suit + exoskeleton + DJ so in the end it might result in enough firepower to take down Queen. Looking forward to seeing how he plans to take him down.