My experience was very different from what other reviewers are saying, so perhaps it depends on your tour guide. Mine was very knowledgeable about animals as well as local history. We saw agouti and an alligator, and I learned a lot about the native plants.
The hike itself is simply a hike through the woods (I was given a choice of bike, walk, or electric vehicle) and is very east. The "uphills" are a joke - I wouldn't have even called them hills if the guide hadn't been duty-bound to say, "And now we're going to go uphill." Yes, it's a five-mile or so walk, so if you can't do that at home, it won't be any easier on vacation.
The water was so high that the very end of the trail was actually a short kayak trip. We then transferred to a motor boat and toured around the islands. Typically, the guide said, we could land at the parrot island, but the water was too high. (This is very unusual. Someone else told me that, on the Argentinian side, Garganta do Diablo was inaccessible.) Finally, we docked and took another, quite short trail back.
In terms of scenery, this doesn't compare to the falls themselves, but it was a nice walk and a very educational experience.