Well basicly, you should try and avoid them all, since everything makes it harder.xD
Also, as I told Century, Ice makes you speed up, mud makes you speed down, bats make it hard to jump high enough.^^ But i'm going to add a legend , ^^
Are the walls supposed to be an obstacle? I get through the objects fine it's just the damn walls that get me. As other people said, higher sensitivity would be nice.
This has been adjusted in the latest update :)