I used to fly in and out of there all the time. Yes, it is small. But that is sometimes a good thing. The one downside or at least from a few years ago is that the Delta flights were often delayed. But same is true for ECP.
It actually shares runways/space with Eglin Air Force Base.
If you head to Destin via Ft Walton(west) rather than taking the toll bridge (east), watch your speed through Shalimar, they check there.
There is a bar that has both airside and pre security accessibility.
For Destin, I think it is the best alternative. Maybe if you were headed to Sandestin, you could conside ECP, as the drive is nice. But no upside to the airport itself.