I've spent over a year on P3 (FES), in it came out in April 2007
Not playing it all that time, I stopped a couple of times. I still have the Episode Aegis last boss to do before I'm done with it. Though I doubt most people are as slow with it as I am
In English, they all seem to get the 'Shin Megami Tensei' title, but while they share elements, technically they're different series (SMT, Devil Summoner, Persona, Digital Devil Saga).
I saw earlier that it was in two parts? Wtf?
Persona 2 is made up of Innocent Sin/Tsumi and Eternal Punishment/Batsu, but only Eternal Punishment was released in English.
If you're expecting a lot of Dante in Nocturne, you might be disappointed there. He is only a quest character, and not so integral to the game that you can't take him out or completely replace him with Raidou from Devil Summoner (a la Chronical Edition). But I think it's still worth playing for itself, as long as you don't get one of those people who try to sell it for hundreds