So Fairy Tail is likely my favourite series, I've loved it since I first picked it up. I didn't actually know about 100 years quest until I saw it come up on my usual manga site.
I could immediately tell that it was a different artist and writer- the characters have said things that seem really out of character, the art isn't as good. And it just seems forced. There are times when it seems far more like fan fiction than a continuation of the story. Fairy Tail is one of the few series that would really get my emotions involved, but this series just doesn't.

And then the story...
**Very minor spoilers***:
They have a lot of explaining to do about the pentadrakes, especially considering Acnologia's desire to wipe all dragons out. And Gildarts had taken on this quest, never bothered to tell Natsu he was hunting dragons (which at the time Natsu didn't even know still were around). And then he faces off with Acnologia, so surely Acnologia knows of the pentadrakes?
Igneel never bothered to mention his own son to Natsu?

Then there's Touka. She's going after powerful mages, but never went
after Alvarez? You know, the whole city-state of powerful mages? Perhaps she feared Zeref, but Zeref spent a lot of time away from Alvarez.

And why would Jellal not bring concerns to Makarov?
There had better be a romance scene with Jellal and Erza. To me that was one of the more disappointing parts of the last chapter of Fairy Tail. That had been building for the whole series, then at the end, nothing?
***End Spoilers***

I trust Hiro Mashima, I've enjoyed all of his work, and I know he's still involved in Fairy Tail, but his focus is on Eden's Zero. So I want to have faith that it will improve, but it's not looking that way thus far.
So in summary, if you really need your fix, I suggest rewatching or re-reading. Unless some major changes take place in the series, it's not worth it. I'll likely keep reading out of some hope it will get better, but I don't recommend that to others!