We've stayed at Ft. Desoto twice since we made the TT plunge about a year ago. TL;DR - great park, plan ahead to get reservations.
Long version (as this has turned in to more of a review than I planned on.) Geez, I'm long winded sometimes.
Far from any kind of an expert on the park, but some observations. . .
We have 2 dogs so we have to reserve in Area 2 on the map - sites 86 through 164.
Turns out our two mutts aren't water dogs, so the dog beach isn't a huge draw for them. That's OK though - they (and we) get plenty of enjoyment just taking walks through the park. Along with just getting a break from the hustle and bustle of daily life that a camping weekend brings.
As for the other items that others have brought up. It's a county park, so residents of Pinellas county get a 7 month advance reservation window. The rest of us (even FL residents) get 6 months.
And yes, the reservation system is less than intuitive. What's worked so far for me is to download the park info pdf, and then have it up in a separate window/tab while navigating the reservation system.
Once you have a reservation, do realize that there's no 'overflow' parking at the campground. For one visit, there was barely enough room for parking a rig to check in since it was busy. So if you're thinking of arriving early, be aware. There may be options for early arrival parking that I'm not aware of. As residents of the county next door (Hillsborough) we just show up at check in time. If you have questions, best bet might be to make a phone call and talk to a ranger.
Raccoons haven't been an issue, at least in the pet friendly area. As others have said in previous threads - presence of pets may be a factor.
There are actually two dump stations on site, which is a little unique and kind of nice.
Sites are packed sand and generally level. You will be tracking more dirt into your rig than you'd maybe like though. In addition, getting in to a site may be a bit tight - not shown on the map are the locations of the ash cans and trash cans. You may have one to keep on your radar as you're backing in.
All in all, we like the park quite a bit so far and no doubt we'll be staying there again.