It doesn't smell - the bag its completely sealed so no smell escapes from it. When you empty it, the output does smell, it is poo after all, but mine smells more like what I have eaten than the usual shitty smell. Different foods make your output smell different. Fish and eggs cause a pretty disgusting aroma, but generally the smell is not as bad as the normal smell of poo!
It does make noises! My farts go into my bag, so it makes farting noises sometimes which is pretty funny! As the bag is hidden under my clothes, the noise is muffled somewhat, but occasionally it makes a huge farting noise that you can't hide!
I'm pretty lucky with what I can eat. They do warn you that certain foods can cause blockages (e.g. sweetcorn, nuts, seeds, mushrooms, leafy vegetables, vegetables with skin and popcorn as they are hard to digest). Personally though, I can eat pretty much everything I ate before - although I do steer clear of nuts, seeds and popcorn. No point in risking it. As long as I chew, chew and chew some more, I'm OK with vegetables etc. but they do tend to come out pretty much as they went in!
I have only ever had 4 leaks and 2 of those were in hospital following surgery. The ones I have had at home were caused by my output being really watery and seeping under the flange while I was asleep. Once you have found a system that works for you, you can pretty much eliminate the possibility of leaks. Some ostomates do struggle with leaks a lot, especially if their stoma does not protrude enough - some have stomas that are flush with the skin, or even sit below the skin, but mine pops out around 1.5" so I don't tend to have many problems with it.