We have them in CA as well. I think in general they're a good workaround for getting things passed that the legislature for some reason doesn't have the political will to work on.
On the downside, repealing these things usually takes another ballot measure (the legislature can't touch most of these), so if one passes that turns out to be a bad idea, it'll be harder to remove it. Unfortunately we do have a few persistent ballot measures that have been on the books for years that are detrimental, but there's no will to get rid of them (Prop 13, I'm looking at you).
Occasionally I'll vote "no" on a proposition that I agree with, simply because I believe it's something that the legislature should take up, and doing it through the ballot measure process will end up being too inflexible.