I actually like Japan, myself, but i'm not a big fan of the religious trait, i guess cuz i usualyl only make 2 Government switches in the entire game ( Despotism to Monarchy and Monarchy to Communism) because i'm such a warmonger, and as a side affect of raising so much hell i usually get lots of new luxuries to keep my people happy without temples and whatnot, and with Governers helping me manage my cities i never have them go into a state of rebellion. But i am a big fan of Militaristic, because even if you are rich and happy, going for a Spaceship or UN victory living your life in peace, outta the blue a Militaristic Civ attacks you and sacks yer towns and takes yer goodies and because you built this nice big infrastructure of Cathedrals and aqueducts and stuff, you are unprepared, and the less advanced civ next door doesn't have all that stuff but has a huge military and takes you down. I've had that happen, it sucks!
I think Industrious is a great trait, but it just doesn't seem to turn me on that much, i just don't think that building roads and clearing forests faster and some extra commerce offsets the need for a big advanced military (I am obviousely referring to my personal favorite, the Germans)
I think the expansionist trait is good, but only at the beginning so you can get an idea of your surroundings and where to build your first couple towns, and of course goody huts, but i think its just too short-lived to be truly useful.
I don't like commercial at all really, i just don't like. All that trading with other civs and having happy citizens is great, but a sneeze between leaders could cause a huge war and all of the sudden your commerce trait ain't to useful because you're fighting for your life and producing extra commerce in your center square won't save you from those damn Chinese riding into your town and killing people.
Thats pretty much my view on things, notice i lean heavily towards military action, because i believe when all the smalltalk and diplomatic agreements are done, you never know when a war is gonna erupt and all the sudden all this stuff that you've worked on over the centuries is moot unless you can defend it with a nice big military. Even if you don't wanna be a warmonger the militaristic trait is still cool because say you're Rome, and you want to lead a life of peace and trade, eventually leading up to a UN victory or CUlture Vic or something, but you don't wanna be conquered in the process, the Military trait can help you to defend against threats from other warmongering civs, so thats why i almost never play a non-Military trait, though i do like the occasional game as the peaceful Indians or Iriquois.