The Tren Maya is one of the signature projects of the previous Mexican government. While there are some good points about the system there are still many shortfalls which perhaps can be ameliorated in the future. First the good aspects: The trains as would be expected are new, clean, comfortable, reasonably quick and certainly far better than Canadian North American cousins have to offer. The not so good: The stations are all located quite a distance outside of their nominal destinations. Shuttles are usually arranged at larger centres such as Valladolid, Mérida & Campeche but the connection can still be pretty laborious. Door to door times cannot compare to taking the very comfortable ADO buses. Door to door from Mérida to Campeche or Valladolid can be as much as twice the time compared with ADO. An additional advantage of ADO is that the buses run very frequently throughout the day and night.
For the average Mexican the Tren Maya is not really an option for regular travel. It is geared principally for tourists and specifically foreign tourists. Even for tourists the novelty of taking the train is gone after the first trip and thereafter buses are a much more practical choice. Buses are also far cheaper for tourists as the Tren Maya has a foreigner surcharge on all tickets. Finally, most bus terminals are located either downtown or pretty close by.
Another issue with the Tren Maya is the ability to easily book trips. The official website page leaves much to be desired and often the option to buy tickets online is not functioning. There is an app which looked promising but as of this writing it was down for technical issues. When it is working it is the best option for purchasing tickets. For the future if the connections from the stations are improved and service frequency is increased perhaps the Tren Maya will be a viable travel option for more people.