I don't really see how P3 was emo. And "pop"? You mean that it had J-pop in the soundtrack? I find that a pretty weird thing to complain about. It's like saying that all games of the 16-bit era and before were bad because of "that repetitive midi $#!&". J-pop (as well as the other musical genres such as rock and hip-hop) really suit Persona 3 because it's set in modern day Japan, just like using classical music suits DQ because it's set in an Old European setting (though to be honest, it'd be more like lyres and things like that, rather than fully blown orchestras).
As for the emo thing; the storyline is less emo than, say, Saro deciding to KILL EVERYTHING because BAAAWWW a girl I met a few times was killed by those humans WHO JUST DON'T UNDERSTAND ME! See, you can make anything into emo; admittedly, it doesn't take a lot of effort to do that to a white-haired bishounen elf-boy who has decided to hate an entire civilisation - no, planet - because a girl he liked got killed. The only things that could be considered emo about P3 are stylistic things; the main character's haircut and the way in which they summon the persona. SMT designs have often looked emo, though. Look at the characters from DDS or SMT3.
Anyway, to answer your question: Yes, P4 is a lot better than P3, especially from what appears to be your point of view. The hero does not have hair over one eye and no one puts guns to their head to summon the persona. Worried Mothers Of America, rejoice. From most peoples' point of view, the improvements include such things as, well... Everything. The S.Links have been overhauled and made a lot less linear, there are now several dungeons rather than just one massive one, the plot isn't based on moon cycles so it flows more naturally and less predictably, the hero has a family now which gives a good emotional basis to the game, the other characters seem to have more to do in life than just stand around in the lobby of a tower block, it's more down-to-earth in the sense that they're countryside school kids rather than part of some elite special agency... There's also more to do with your time, such as take part-time jobs, some of which lead to S.Links, and there's a fishing minigame which can get you some very rare items.
I haven't played Persona 1 or 2 but I am looking forward to playing them. You probably know that Persona 2 came in two parts but only one part was released in America (and then quite laughably localised; e.g. they coloured in one of the characters brown and changed his dialogue to be stereotypically African-American...) The other part was only ever released in Japan but a translation patch for it has been released so now us English-speaking folk can play it. If you didn't know that, here you are - Happy Christmas: http://tsumi.wordpress.com/
I've found translated roms for the earlier Personas on a PSX emulator. Check them out when you can.
I couldn't get the feel for Persona 3. I don't like J-Pop and the whole putting a gun to your head made my friends and I laugh. Not all games are meant for everyone, so I hope your not upset by my comment. But man, from what you just told me, Persona 4 sounds mondo cool. I guess I'll pick it up sometime this week when stores Re-open. I'm running out of things to play and a new SMT game definitely needs to sit on my shelf. Devil Summoner was my last game I beat and continue to wait patiently for any other games to be announced.