So what's new?

[Tavrobel]

tl;dr, not really. If you need (i.e., absolutely need) an MMO fix, this could work.

The game plays like it was made in 2004. Single actions all share a global cooldown and no movement during the channel time. Very few instant or non-global cooldown spells. If you're looking for a sandbox, this isn't it. If you're looking for tons of high-level raid content,this game only has 5 major instances, with the Bahamut Coils. If you like pretty landscapes and walking around a lot, this game has that in droves.

I'm not going to tell you that the leveling process is exciting (or fun). Combat is auto-target with the ability to cycle through targets, no accuracy check. Tank-DPS-Healer meta, with everyone being trash at off-role-ing (exceptions, Scholar, Summoner, Dragoon).

The only resembling-new thing is the crafting system. Your ability to craft is tied to an EXP system that resembles combat more than the old sit-in-town versions. Higher level combat zones also mean higher tier drops, and some resources can only be gathered in a particular crafting class (or purchased wholesale from the market/trading post/auction house). You do have to pay attention during the actual crafting process but you're still sitting in town doing it.

I honestly would not recommend this for some who is looking for anything "new." It isn't. It mostly fulfilled the role of being one of the two big name MMO releases in a year where there were not any releases. Never winter covered March/Spring, and FFXIV covered the end of Summer/August. On a scale from 1 to 10, this game is extremely close to release-WoW-clone and kinda far away from GW2 and old-school MMOs.

EDIT to actually answer questions:

It's better to solo until you absolutely need to in order to do the low-level dungeons. Grouping is done via automatic queues, and will split you into Tank/Heal/DPS/DPS, unless you have a pre-made composition planned with people in your guild or friend-list.

Grouping is relatively painless, just the hassle of having to deal with other people. Raiding is limited to time-sensitive Bahamut Coils, which as of this time, only one group has officially defeated. More content is soon to come, as well as new people who can complete the Bahamut instance.

The world is large, and pretty; aesthetic, but it gets in the way more often than not. There's grassy land, grassy knolls, forest land, tree-but-not-forest land, deserts, swamps, seafarer towns, barrens, snow land, ancient ruins land, and giant-crystal-probably-caused-these-ruins land, along with the occasional highly militarized fortress. My personal favorite environment was Brayflox's Longstop, a swamp filled with rainbows and a dragon AND RAINBOWS HOLY CHRIST RAINBOWS.

Major cities will have lots of people AFK or shouting. Some zones have trains of people running around, EXP grinding the dynamic events (FATEs). You shouldn't feel lonely, but it's well past release date. Anyone who is still here is likely someone you'll continue to see, which bodes well for SE's financial statements. There's lots of things to explore, but no reward for doing so.

The game is not difficult. Including the raid content. If you're wondering why only one group of people has completed the final instance, it's because the game is more a gear check than actually difficult. Nothing catches you by surprise the moment you learn about it. The most cynical version is that SE intentionally bugged turn 5 to be non-completeable, as the only group that completed turn 5 has not published how they did it.

Unique classes, not really. The closest would be the Scholar and Summoner, in my opinion, a Healer with off-DPS capabilities, and a DPS with a pet that can DPS, tank, or very DPS. Since they're tied to the base-class, Arcanist, they are always the same level as each other. If you level a Scholar, you're automatically leveling the Summoner, as well. Cross classing abilities can be pretty important. Fortunately, you get an EXP bonus if your current class played is not your highest; practically, this means once you have one level 50, every other class levels faster, including crafting classes.

It feels like a Final Fantasy if you're looking for the previous-entry references. Otherwise, no.

Tradeskills? Not sure what you mean here, but if you want to know about the gathering and crafting classes, they're like the combat classes, but without combat, and have their own EXP gain. Switching between any classes isn't difficult, as you can just wear a different weapon to change your class. The hard part is keeping track of your gear.