There have been a lot of these crossovers, where super-heroes from one company or universe meet another hero or adventurer from a different universe. Most of them are passable at best, but Dark Horse has a fairly solid track record, and Superman/Tarzan is right in line with some of their successes like Superman/Aliens or Batman/Tarzan, which had beautiful painted work by Igor Kordey. Dixon is the perfect guy for this sort of pulp adventure story, and his take on Kal-El as the lord of the jungle and Lord Greystoke as bored city royalty makes for a fun read. I'm not as impressed with the artwork by Carlos Meglia, whose work has an animation quality at times but whose stylistic tics don't really click with my particular tastes.
The basic concept is simple, based on two changes to the timelines of these two heroes. First of all, Tarzan's parents manage to convince the pirates to sail them back to civilization rather than killing them or abandoning them to the jungle. Second, Kal El of Krypton lands not in Kansas but in the remote jungle. The adoption that is at the heart of both origins takes place, and it is here that one of the few similarities shows through, in a clever bit of writing from Dixon.
In addition to the notion of being adopted by natives of their new habitats, Superman and Tarzan do share an outsider point of view. Seeing Kal-El develop among the animals as not just a human but a superhuman gave his outsider status a boost, and while Tarzan became a leader in the jungle because of human skills like intellect, tool use and opposable thumbs, Superman has the additional benefit of strength greater than any animal, durability that means he needn't fear the animals and several other abilities. His inability to understand that he is truly an alien, not a brother to the various humans he finds either, makes for some poignant moments in the story.
This isn't just "What If Superman were Tarzan" though, and so Dixon brings Lord Greystoke back in, setting up the story so that it was his destiny to become a jungle lord and not landed royalty. I'm not so sure I buy into this destiny riff, as it strikes me as the "things all wind up the same" ending that generally happens in too many Elseworlds tales, but Greystoke's wanderlust and adventurous nature do fit in with the person he might have become had he followed his legendary path, and it makes for a fun meeting between the two icons.
Where the book really doesn't work for me, though, is in the artwork. Meglia's work is in the cartoony vein, and it strikes me as the kind of thing that can't hold up under the kind of detail he's asking it to have. When he's focused on simply one character or some simple movement, the style works great... it's like animation storyboards. Most of the time, however, there are a variety of heavy background elements that all blend together, and his over-exaggerated anatomy and dynamic movement is distracting more often than not. In addition, and this is a fairly specific complaint, his style of drawing hair, whether it's arm hair or beard growth, looks like worms... it's the best example of a specific weirdness in style that doesn't fit my sensibilities.