I'm not familiar with the program at St. John's, but I think you should definitely try to get into contact with students currently in the program (or who have graduated from the program). I believe they will be able to best help you in terms of the quality of the program instead of listening to "rumours" from people not in the program.
Also, did you talk to any current graduate students in the program during your interview day? Perhaps try to get into contact with them via phone/email? Or email the program director and ask if they can provide you contact information for current grad students as you need more information before you make your decision.
I know entering a PhD program is a really big commitment and its super important to know what you're getting yourself into.