I own four different Tomb of Annihilation supplements, and this is the only one I'd call a must-buy for running the game.
If you want to provide yourself with many more interesting options for travel days, including unique discoveries of flora, fauna, and both roleplay and combat opportunities, this PDF is a must-own and well worth the price. This alone would be worth it for me, but add onto that some truly ingenious expansion of the dinosaur racing (should be tons of fun to run for the players while also introducing them to some of the Port's major sights), and some twisted ideas for introducing a certain trio of Sisters that can play a role in the later campaign.
I've purchased all the companions this author has provided for WotC's campaigns over the last few years, and every one has made my game better for myself and my players. Buy his stuff because his ideas are worth it.
[5 of 5 Stars!]