An Odd Meeting...

Firstly, well done for managing to put in a great majority of characters without the scene appearing /too/ cluttered and messy. The characters are easily readable and the manner of placement has nicely kept the similar colours away from each other.

That said, its generally wiser to open up the composition and the scene when your dealing with such a large amount of characters and in this instance when you take into consideration their size in respects to their surroundings.

Scale can be a difficult thing to get to grips with and convey accurately, try thinking of things realistically. For instance, the trees are either very small or these felines are very large.

Continuing on a different topic is your use of Photoshop brushes which is very recognizable on the tree-leaves and the grass. Its simpler and quicker possibly but your not really flexing your artistic muscles by using them. Try developing your own technique for grass and leaves, something that draws not only from life but also from your own style of drawing to make something much more unique and pleasant. The brushes don't really lend anything to the rest of the scene.

There is also a distinct lack of shade or form in the characters which seems odd when compared to the fact that some areas are indeed shaded.

Shade brings out tone and form, it brings life to the currently rather flat characters. Remember, even darker characters like the black and white feline can still show highlights and shade!

Its obvious you've spent some time and effort on this but you need to keep pushing yourself! If an image is taking too long, save it and come back to it later, don't try and force yourself or you'll just burn out.
Keep up the good work!