Hi Kirby;
I've built one Arii kit (and have a couple of others to do) and found it not a lot of trouble at all. I found fit to be very good, detail levels were generally good, though perhaps the wing ribs on the 1/72 Willow K5-Y Trainer Biplane to be a little too stark and noticable. I do recall that the plastic was a bit brittle bu tnot too bad if care was taken.
Their instructions were fine but colour call-outs for things like interior details were a little vague and generic.
Colour schemes and decal options were nice and Gunze Colours were recommended IIRC.
Decals responded well to setting liquids though they grabbed the surface of the model a little too quickly for my liking and needed lots of water to manouver them about on the model.
Overall, I liked the kit, it was a relatively nice build.
I did no accuracy checks as my info on the Willow is limited.
The piece of trash linked below is my Willow build on Ross Moorhouse's site.
Neil's Kawanishi K5-Y Willow
HTH
Neil