I haven't started at ZJX yet (FY2012.) Worked at ZMA for several years and it was ok. I hear ZJX is better staffed and a more pleasant facility to work at, respectively.
Lived in Jacksonville for 8 years prior to working at ZMA. It has a unique culture with lots of rednecks, religious people and Navy folks. The city is as geographically spread out as you could imagine and as such it is hard to define any particular aspects of it accurately, e.g., the beaches are very different from the southside or downtown.
Low cost of living, nice weather and big money job = happy life.