Very nice :)

What a cute design. I really like the first lighting set up a lot.

The one on the top right does the best st hi-lighting the character, it also seems to suggest a focus on scratching post as well.
Check that the specularity on the bamboo is being affected by the alpha channel.
I feel it could do with softer lighting and shadows over all, though I would try and maintain that darkness on the wall that really makes the character pop on the top right one.
She scene overall doesn't feel as tight as the concept Try pushing the objects closer together and more towards the corner, then narrowing the focal length on the camera.
I liked in the concept how the bamboo curved in to sort of form a natural vignette along with the spot light.
This 3D version has lost a lot of the vibrant colors the concept had, if you can get come of the purple back in the walls that would really help. you can probably do that either with the actual color of the walls, the ambient color or just adding a color grade on top of the final image. Oh and the navy accents on the ends of the characters limbs are almost non-existent now.
I hope I actually mentioned something you weren't already aware of, and sorry for the disorganization of my critique.

>The one on the top right does the best st hi-lighting the character, it also seems to suggest a focus on scratching post as well.
Good good. Because I don't think it's really coming across as a scratching-post/training-dummy so a little focus will make it look more like his opponent.

>Check that the specularity on the bamboo is being affected by the alpha channel.
Yep yep, I fixed that already in the last 2 shots as you can see.

>I feel it could do with softer lighting and shadows over all, though I would try and maintain that darkness on the wall that really makes the character pop on the top right one.
So far I've added a really faint directional light to colour the shadows, and an extra light to just give the plant in that corner a bit of light so it's not black. It seems to help. Maybe the rest will have to be handled by AO and zdepth passes. I need to do an ugly version with all the cheap effects :P

>She scene overall doesn't feel as tight as the concept Try pushing the objects closer together and more towards the corner, then narrowing the focal length on the camera.
I will try, but some of the crampedness is honestly physically impossible. I wish I'd had the time/speed/perseverance to model all the nice plants to frame him but I don't think its' going to happen.

>This 3D version has lost a lot of the vibrant colors the concept had, if you can get come of the purple back in the walls that would really help. you can probably do that either with the actual color of the walls, the ambient color or just adding a color grade on top of the final image.
There will be post, In don't think I can get that colour look without, unfortunately. But post and compositing is part of the course so EH. By the way, ambient lights really kill things, a directional light at low intensity and no shadows works though.

>Oh and the navy accents on the ends of the characters limbs are almost non-existent now.
Yup, I redesigned him.

>I hope I actually mentioned something you weren't already aware of,
Very little D:

Here's a little learning experience that you can do with lighting :D

Try to replicate the amount of lumens are in any room in your house or anywhere.

(P.S. I use math with lumens, GPS, and Earth rotation (AKA Season))

If only the maya lights weren't with completely scaleless units :B

Gotta try Cinema 4D sometime :P
I made that transition from Autodesk to Cinema and I love it since it's all in one.

are you using maya or max?

It's in the description. (also, mental ray)

duh ok, so maya and mental ray. you want to keep a cartoony look/light or go for something more realistic?

Just something believable, and soft.

if you dont mind my input.

you may want to use area lights (a triangle light basic setup for example) , each with a mib-blackbody: mib black body goes into the arealight color

in order to see the light take effect you are gonna needa new camera (shotcam) with a mia exposure photographic":
the mia exposure photographic, goes into the mentalray dropdown menu of the camera atributes, and goes into the lens shader.
once thats done go into the mia exposure photo atributes and in whitepoint add another black body.

now you have your tools ready, but at this point the render should look completely black, which is normal. what you have to do now is adjust the camera atributes. keep in mind that ll these lights and the new camera work like real life lights and cameras, meaning you will have to play with the exposure, film iso, the camera shutter etc.

any way, in orther to start geting results in the render, just go to your new mia exposure photo nod and crank up the CM 2 factor quiet a bit, I have mine at 15000.000

this are some heavy renders so you may want to take small renders first to speed it up and get small but fast previews. try this if you want to :) and if you run into any problems let me know, I like to help

forgot to mention, all this nods can be found in the mental ray hypershade menu:

mib_blackbody-mentalray lights
mia_exposure_photografic-lenses