If you previously played Shin Megami Tensei: Persona 3 or FES, Trinity Soul is not based on that event but happens 10 years afterwards. This anime series doesn't follow or add to P3, the events before aren't mentioned at all. A characters are introduced, Shin together with his friends Takuro and Megumi which are all persona users. The story doesn't focus on these characters only. There are others who are given more important roles in certain episodes. If you played P3, you'll recognize a certain character.

Trinity Soul is a 26 episode anime which genre are mostly mystery, supernatural and a bit of school life. While the story isn't as deep as you could expect, it's still interesting with decent amount of surprise. This time around the personas are summoned without evoker or anything strange, just by focusing the persona comes out. None of them is a special one, but Shin's persona has a special sword and Jun's (shin's brother) has the ability to calm personas.

Disappointing that it doesn't build on P3, but it's worth checking out.
My score = 83 / 100