Really love the Trilogy! As a starting adventure for tier 1 play A Day at the Races delivers an interesting and different experience for players, but will require a creative and prepared DM to ensure a high caliber experience.
I like the diversity of the experience, the betting, the race and the battle; however, each could use a bit more flavor. The experience of this adventure is almost completely in the hands of the DM. Without the DM adding flair to the races--having to fill in mechanical flaws, describing a short series of checks to add drama and coming up with more detail to add to the extremely general winning conditions--this adventure will most often fall flat for the players.
I would suggest any DMs prepping this adventure to reuse or reference mechanics from 07-01's race to fill in the gaps, especially with the final stretch of the race.
I also prepped some bookie/betting tickets to add some flair to the first part. If I had more time to prep I would have maybe made some ribbon tokens to give to each player in the second leg, as they have a gold value, and some scrabble type pieces to represent the bricks they fetch from the harbor to make the experience more tactile for the players.
In the final fight I maxed the encounter challenge as the players had no prerequisite combat. It also adds a more satisfying crunch to the finale with a better XP award for their mostly roleplay experience.
This is neatly wrapped in a 2 hour session. The timing for the module never really feels rushed as the DM holds all the sway on the pacing.
The Trilogy, The Jungle Has Fangs is great as a whole, a well paced hook to get new players invested in season 7.