There are quite a few people on Mysidia, and we have a fun time. The hardest part now is just getting started, and most people no longer have a low level job, but if you are willing to powerlevel to 40, the game becomes much more partying... Currently most people only party ~40+, and there is almost always a party available at that level.
I could be biased though (level-wise).
As for leveling in general (and I have either soloed or duoed most of my levels), after level 20, leveling becomes somewhat easier.
As for gear and equiptment, I have found that the NM gear works right now, and is very easy to get (if you can get some help from a person above level 40), and leves (especially company leves) are very handy for getting experience (I just did two company leves at 48, and was able to get 30k exp, but that has more to do with the level, at lower levels you will get more like 8-12k a leve if you have guardian aspect and can do it 1-3 above your level).
Exp chains really help, as do skillchains. The best way to handle chains are balancing your TP/MP for a last push at the end of the chain when soloing/duoing.
Thm is still over powered (obscenely so), but, soloing, they can get through a few mobs before running out of MP, or in a party, if they get over-zealous, they will get geeked something fierce.
Gld can tank now, quite well.
Mrd is not that great of a backup tank, but, they can hold their own, and especially at later levels, they have some impressive dmg. Not as much the aoe destroyer they used to be.
Lnc so far is definitely the TP manager. The change to Invigorate is more impressive to me than anything else I have seen from them, and that ability is definitely a necessity.
Con is the healer, hands down, no question about it. And they are definitely impressive as to how they can destroy Gnats and lightning elementals. Their earth damage is great to say the least. And the fact that everyone can use protect, but only Con can give the magic def boost (and if another party memeber casts protect after, they will overwrite the shell status, makes party balance and skill appreciated).
Pug, I haven't done too much with, however, their attacks are fun, and feather foot is an impressive ability in any situation, and second wind is more useful than ever.
Arc, I am just leveling that so I can get my crown... but, it does have some impressive abilities, especially bind. Properly used (which it is VERY rarely done right now), it is very handy as a controller. Their ability to kite can not be beat.
The Class balancing has done quite well. Now, they just need to iron out some of the combat aspects from legacy mobs and abilities, but other than that, character uses are starting to take their shape. Add that to the fact that players now need skill to participate successfully in some fights (the Strong Hold and dungeon raids, as well as the two primal battles), you can still just get a group of friends together and beat stuff up if you want.
Quests are a lot more prevalent than they were when the game was released. Unfortunately for me, I have been able to keep up mostly with the rate they are released (I only have the Mog fight, and my last Grand Company promotion left, and one last live quest, I am hoping will still be available after the update, though I doubt it).
Anyways, I hope you enjoy. There is still much work SE needs to do, but, its definitely not the game they released a year ago.