I live in St. Augustine, about 1/2 hour south.
Jacksonville is a rapidly growing city, with a lot of the "normal" issues associated with that. A LOT of infrastructure construction is going on, mostly in an attempt to put on a modern face for the Super Bowl, upcoming this next year.
The downtown area is mostly daytime business, with not a significant amount of entertainment after hours, compared with other "big cities". Until the last 2-3 years, downtown living was almost non-existent. New, VERY expensive condo projects are now underway, which should (hopefully) breath life into the city center.
Minor league hockey & baseball, NFL Football (sort of

). College football is BIG in NE Florida (university of Florida, Florida State & UGA founds abound).
The school system is superior in St John's County. To a significant degree, the north end of my county is a "bedroom" community because of our school system. Live here, go to school here, work in Jacksonville.
Housing is cheaper in Jax out in the 'burbs, but housing prices are on a steady surge. They might or might not be cheap compared to where you are now, but to us it is getting ex-pen-sive. My house has appreciated in value approx 18%/year for the last 5 years.
Ponte Vedra is in St. Johns County, not Jacksonville. Veeeeeeeery
expensive housing. The "old" money is there. The "new" money is farther south in St Augustine area & the World Golf Village.
Climate? I think we had 8 nights last winter with freezing temperatures. Be warned, in the summer the weather is Hot & HUMID. If you are not used to sweating, it will take some getting used to.
The military is a big presence in Jacksonville, with NAS JAcksonville & Naval Station Mayport both being in town What used to be Cecil Field Naval Air Station (which closed 5-6 years ago

) is now Cecil Industrial Park, with a fair amount of aviation & High-tech industries there.
Good luck in your decision.