I think I'm like an hour away from finishing the game. Unless the final boss leaves a really sour taste in my mouth, I'd say this game has been beyond my expectations of being a fun and decently challenging FF.
For the record, I really enjoyed FF4AY as well for its challenge, beautifully animated combination attacks and the huge cast. However that game suffered from countless flaws with the most offensive ones being overly recycled dungeons between episodes, 99% recycled enemy sprites from FF4 and a shitty story.
While I wouldn't say FFD has a ground-breaking story (it really doesn't), I didn't find it too offensive, even though the last chapter of the game was a fairly big let down in terms of narrative and character development. Most enemy sprites are originally drawn for this game, even if they were staples of the series. I thought it was cool that they did not throw too many palette swaps at you, until that all changed in the last 1/4 of the game. I missed having to fight enemies unique to the last dungeon like it was in FF4.
The job system this time is both an improvement and a downgrade from FF5. It's an improvement b/c it has a wide array of fun skills to muck around with. The existence and general usefulness of Fusion-abilities makes raising the less useful jobs less useless which encourages more experimentation. Having said that, the player has to invest more time than its worth if he wants to experiment, since every job initially only has 2 ability slots which can be consumed easily with only 1 action ability, so you do not have any room left to tack on other support abilities for customization until you level up that job to open up more slots. That leads us to a common complaint about the non-necessity of JPs which serves as nothing but annoying and artificial roadblocks to leveling jobs.
There are a ton of unique dungeons in this game - 40+ when I counted. They might not have a lot of character visually since they share maybe 5-6 kinds of tilesets + palette swaps, but many of them have enough little gimmicks to make them less tedious. There are also no back-tracking or very little retracking of dungeons unlike FF4AY.
Most people I hear think that the game is rather on the easy side. I don't see myself as a bad player at all, however, I have wiped many times at many different bosses and I enjoy the challenge immensely. Enemies and especially bosses require different strategies (well, as different as FF's ATB system allow) to beat effectively and I appreciate the variety of patterns there. This is, again, true only until the last chapter when I have a Seer who can dual-cast and I believe mostly for that reason has made all the boss battles a little samey
Curega + Curega/Raise/Esuna saves my ass so many times it actually got kinda boring.
Though I am a bit disappointed with the last chapter of the game, where the good parts lose some of their charm, ironically when it should be the most fun when you reunite all your party members, the flaws do not truly overshadow the good parts and I heartily recommend this to people who prefer the "traditional" FFs. Hell, I even prefer this to Bravely Default as I find that game to be semi-broken in the last chapter - I guess it's not easily to wrap up a game nicely in the end is it?