We've been going to Fort Myers for years and this is the first time we visited the Slough, mainly because we didn't know it existed before.
It's free to go in and the parking is reasonable. We went twice, the first time by ourselves, the second time to take the free guided tour at 9:30 so we could see and learn more.
It is a wonderful place to visit. The scenery is wonderfully serene and the boardwalk makes it easy to get around. I took tons of pictures, as every view seemed to be worth recording, both of the swamp areas and the ponds. Although there is lots of standing water, the environment is such that there are few if any mosquitos which is a big plus for me!
The guide on our tour could not point out much wildlife but showed us so many interesting plants that we didn't feel cheated, and there was an area by one of the ponds where a telescope had been set up and turtles, gators and lots of birds were pointed out to us there. I guess if you want to see lots of wildlife you need to get there early or late when it's cool and quiet enough for creatures to be out.
In the Interpretive Centre, there was plenty more to look at (and I could buy souvenirs) and the volunteer staff were really friendly, helpful and informative.
Not sure this would be a place for teens or small children, although the six year old in our party loved it and spotted a lot of insects and small creatures on her own. We,as a more mature couple without kids will definitely return the next time we are in the area.