I gave it a 3. The main game was easy enough that I was able to do all normal battles on Hard or higher already, so the difficulty there is null. If you're dedicated about dualizing (running down the list and making new items every time you get new ingredients), then requests will pretty much all be there. Fill in missing items with the Arles pot and you should be fine minus minor grinding. If you're serious about it, then using the +piece drop book as soon as you get it make the final requests cake. I didn't bother equipping it until the end and I only had to farm for ~7 pieces, all of which dropped in under 10 minutes each. Grinding the Arles pot was cake too, just tedious. I had 9100 energy once I finished all other trophies, so getting to 9500 was 20-25 minutes of work and done. The Zoon Cage can be zoomed through at low level on simple difficulty, and Rock Gagan I was able to beat fairly easily. Getting titles was easy too, just switch your main char and spam special moves. I did absolutely no farming for titles and got every title trophy on my first playthrough.
Overall, nothing fancy here. Just be sure you use a good walkthrough to get the missable quests, though I don't think they benefit you at all aside from extra grade in NG+.
Proud owner of Arcana Heart 3 platinum trophy, earned without boosting.
I don't accept blank friend requests.
I also write trophy guides sometimes...