Wat Sangka Thae is one of Ayutthaya's quieter temple ruins, useful precisely because it sits outside the most crowded loop of the historical park. The brick remains and open ground are modest beside Wat Mahathat or Wat Chaiwatthanaram, but they help fill in the scale of the old capital.
This is a stop for travellers cycling or wandering between the major ruins, not a reason to come to Ayutthaya by itself. Give it a few minutes if you are nearby and want a less staged encounter with the city's ruined temples.