I really enjoyed P4G on Vita. I've seen that P3P is only £10 on sale...very tempted.
I know nothing about P3P, but I'm assuming I'll enjoy it based on how much I liked P4G? Or is it just gonna make me want to re-play P4G
Get the game man

! I got it when it was 5 bucks a month or so back and enjoyed it as much as I did P4G

.
The gameplay and design of the game is very similar to Persona 4; you are in a high school setting, you have to build up social stats to gain access curten social links, social links were introduced in Persona 3, and you explore a dungeon location at night with a big 'boss' shadow appearing every month.
What makes Persona 3 different from Persona 4 are a number of things. Firstly, the male character has a stricter way of dealing with social links, meaning for the female characters you HAVE to date all of them. This creates issues where your links will reverse or become broken if you aren't careful, but this can be rectified with the female MC (as her SL's handle the same way they were in Persona 4). Secondly, the dungeons you went in with Persona 4 are one HUGE dungeon in Persona 3 in the form of Tartarus.
This dungeon is randomly generationed like the ones in Persona 4 but you have to explore hundreds of floors and they sadly don't have that much to do with the main story until the end of the game.
Thirdly, the game is much darker then Persona 4, with a story being a strong reflection of that. I would say more but I don't want to spoil the games great story for you

.
Lastly, the visuals in the PSP version (the one you are interested in) aren't nearly as great as they were in Persona 4 Golden and the original/FES version(s) of Persona 3. See, everything but the Tartarus dungeon is 2D art you explore via small circle with the analog stick. You may find this to be an issue but to me, it made the game really snappy going from place to place and the story is told with 2D art anyway in the original, so it isn't that much of an issue. The sound quality is great (with the soundtrack being some of the best I have ever heard in an RPG....even better then Persona 4's soundtrack)...just listen to
this and
this!
For the price you are getting it for, it is an amazing RPG and Altus and the Persona team did a great job making the game for PSP

. It even has extra content from the original game (being able to play as a Female Main Character, more social links for her side of the story, more persona's to use, new tracks for the game, ect).
Get the game man, you will love it

!