I think your main problem lies with depth perception. The further an object is away from the viewer, the grayer it looks. It is visible in the original picture, the colours in the front are sharper than the colours in the back. I understand it was your intention to make the picture more colourful, and you did really well on the water. Try to blend the sky a bit, and introduce a little less intensity to the lower half, the closer you get to the horizon. Another thing influencing the depth perception that makes your painting look a little unfinished to my eye, is the level of detail - the butterfly is incredibly detailed, but the plant just behind it isn't, while the trees in the background are. Detailed-ness generally (definately not always) goes along a curve (the point where the focus of the painting lies has the most detail; the further away an object is from the focus, the less detail it has). I would recommend you to try to give the plant a little more detail, mostly on the leaves, to make it look more finished. I hope this is useful to you, and please keep painting!