That is a really good question. However, I suppose it would depend who intelligently designed it. I think the whole aging thing has to go. I don't say we should live forever, but the falling apart bit as you age is shite. Equally backs are a bad design. Why do we have to spend so much time being told to sit up straight, adopt an appropriate posture, design it so we can't slouch! Eyes (oft quoted by creationists) are rubbish, fail all too often and are far too sensitive to the environment. Talking about that, why did we have to loose our fur? I think I'd look lovely in a nice ginger mane to keep me warm. Did I mention aging? The menopause, they can sack that right off...it's wank and there is no possible biological benefit to messing with women's bodies like that...just cruel. Also why is it I (and virtually everyone I know) love everything bad for me, from cream cake to gin and tonic to staying in bed late. Why do we have cannaboid receptors and nicotine receptors? Pain can go, can't I just get a text, 'Jayne you need to move away from the PC now' or 'Jayne that diet coke will fill your tummy up with wind'!? I also think depression and anxiety are just crap, as are most nasty diseases. They need to go. Also do not design a creature with bits you have to remove, so no tonsils, no appendix, design them with piercings (or the choice), no excess teeth either.
I could go on but I can say this, if there was an intelligent designer he should have his wage with held they made a crap job!