its decent, with some worries on the horizon.
BC (bahamuts coil) is the final endgame, and feels appropriately difficult until the last boss. The final boss feels impossible due to lag/mechanics, however the devs have stated that people are not doing the fight properly and that lag is not the reason they die, so take that with a grain of salt.
Before the final dungeon, the endgame grind is a little high. There are 4 total dungeons at endgame, each with their own merits.
Praetorium - very easy 8 man, boss heavy (6) dungeon, with very little trash - generally ignored - no loot drops at all
CM - very easy 8 man, trash heavy dungeon, with easy bosses - farmed regularly by bad players - no loot drops at all
WP - easy 4 man dungeon, with a few gear checks, but nothing very high, pretty fast (most runs are here) - the loot drops arent that good ilvl 55
AK - medium 4 man dungeon, with slightly higher gear checks. about as fast as CM/prae - loot drops are ilvl 60
each dungeon gives 100 tomes, of which you need around 5000 for a full darklight set, which is your ilvl 70 endgame gear.
In addition, there are 3 primals which are just 1 and done boss fights, giving negligable tomes, but each drop 1 weapon. all 3 are 8 mans, and are easy/medium/hard respectively (ilvl 50, 60, 70). once defeating all 3 and doing a big ass quest chain, you get an ilvl 90 weapon. You can do these alot for a shot at the weapon, but most people blaze thru them, get their relic ilvl 90, then do the dungeons. Titan (the hard) is actually quite difficult, so you need at least some gear before going in (ilvl 60-65 avg), or some gil to just buy a carry.
The last issue is that next patch introduces another raid dungeon, tuned to be EASIER then the current dungeon 80 vs the 90 current. It was originally intended to bridge progression from darklight (70) gear to BC (90), but was unfinished, so they are adding it in here in a month or 2. The next content patch after will most likely contain higher content (4-5 months out)