Even with the darkened and desaturated background, I just can't UNSEE the fact that the tree tops are huge slabs of flatness after it was pointed, especially because the tree bases are so prominent in the picture.

That is me, though.  It may supposed to look like that.

I agree more detail and better shadding for the leaves is required. However I really only think the foreground tree tops needs any significant detail. Too much detail in the background will just be distracting, not to mention time consuming.

I think this big argument over whether or not Adam Atomic was being harsh or not is pretty unnecessary... It’s possible a lot of what PypeBros is saying is getting misconstrued. I take it from his blog http://sylvainhb.blogspot.com/ and his writing that English isn't his first language. Whether or not he was dodging the work doesn't matter now I suppose as he has said he will be continuing work on this or getting someone else to do it.

I'll get back to work now, try to integrate your remarks, work on better animation and palette manipulation tools, add rayman-like animation to the main character, and come back when i'll consider to have any improvement.

From this quote:

I need advices to progress, that's certainly a fact. You gave pretty good ones, and i'm grown up enough to take critics the way they are, even if they are as rude as "less interesting than kirby".

I take it he is mature enough to listen. 
Furthermore the fact he has a blog and a working game engine shows that he must have some commitment to this project. So really I don't think the discussion warrants any more mention.

If someone is not willing to take on advice despite asking for it, it becomes frustrating for those who are issuing the advice. So I can see AdamAtomics justification and I agree some people just need a wakeup call. However in this case I'm not sure if it was necessary. Keep in mind this person is working on the entirety of this game, this is very time consuming so might explain why no sprites are coming back yet. I suppose only time will tell whether PypeBros is taking on bored what we have said or not.
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I just wish people had given crits over the complete character (e.g. the ball with hands and feet)

the shapes are fine, just use the same principles I applied to the blue body to the entire character, furthermore the entire scene. Everything needs its palette reduced and colour selection improved. Rather then going from just dark to light add yellow as you get lighter (highlights), also add blue/magenta as you get darker (shaded), this is known as hue shifts as oppose to straight luminosity shifts. Also dont forget to alter the saturation of colours, you can make the highlights and shadows more desaturated then the midtone to help improve the palette. A lot of this is trial and error.

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see not so glossy, thats all it takes to make it look a little more plastic and less slimey! Removal of 1 highlight in some areas makes it look a little cartoony as well. I hope that gives you some ideas...
Just because you can use a lot of colours doesn't mean you should. Animation for one thing will become a lot harder if you are trying to put loads of unnecessary colours in all the frames, it also becomes harder to make changes to the image. If you look at the two images of my and yours side by side, you might notice mine pops out a lot more, this will make it stick out to the player so he/she doesn't lose it in the environment. Furthermore it gains a better sense of volume/looks a lot more 3dimensional as it is actually portraying where the light will hit it. The ramping of the colours is subtle enough for no one to notice the stark transition, but also bold enough for it to look like a highlight.
I personally am not that impressed with the design of the character/s either the blob seems a little generic and the worm things look, well like worms from the same named game. However if that is the way you want to go, I suppose its fine though something a little more original looking wouldn't hurt.
This post was probably a little unnecassary as all it did was serve to re-itterate what has already been said... But meh'.

It will be when done, but probably wont be done for a week or 2 due to other stuff I have to do. I will send you the link when I put it up... just hope I remember .

Kill like half a dozen colours. You are using way to many and to little effect, organise a decent palette and apply highlights and shading according to the material, in the edit I have made I use 6 colours including transparancy and I chose a liquidy/reflective material. Hence the hightlight underneath caused by light reflecting of the ground. Use a grey background as the placeholder background, the green you have set on right now is way to saturated and will affect how your sprites seem to look.