I applied to MSPP and was recently accepted for early consideration. The interview was pretty much what you'd expect it to be - an individual interview with a professor and current student, a small group interview, and a brief writing sample. The faculty seemed liked they really cared about each student's success and ability to become a competent and sound clinical psychologist. The only "hitch" I've found is that the APA internship is optional your 5th year, and most students choose to graduate within 4. If you're serious about it, make sure you take that 5th year internship. Also, it's roughly $50,000/year to attend and live comfortably each year. They have limited scholarships (which you'll learn about at an info session the day you interview), but be ready for loans galore.
I have no knowledge on Widener, but MSPP seemed like a tight-knit group of people, and the current students all seemed glad they chose to go there. Boston is a fun area to live in as well.