On the one hand, it gimps a lot of features found in the other versions of Persona 3. On the other hand, no Keisuke. Tough call.
He's still there, and still a social link if you're playing a dude (but why would you?)
Also, yes, P3P is better than P3:FES mechanically, but worse than P3:FES in many regards from anything outside of a dungeon (quicker, but lacking in personality and actually breaks some of the better moments of the game). Worth a buy if you don't intend to get FES instead.