My personnal taste : -In the green level, the grass sprites, are too much low polygon, the feeling is polygon , not grass life , i mean, why not putting lot of grass. Like in Supercan A8 game ,where the grass is just perfect Your level is not full of polygons so you can bring on more grass no ? -I find visually strange and not enought natural the grey slopes on the fisrt plan on the grass terrain , why not putting real rocks insteas
Anyway, only few people can achieve suc beautifull levels ! (even me , im'not sure at all i could do as good ! Keep it up !