Hi there,
I have lived in Leeds for around 2 years now and I have not seen anything bad, I have had a couple of friend I work with who have been broken into but that's all and in a city as populated as Leeds I don't think that is to bad. It is mainly down to where you live, if you live in the nice city center apartments like I did originally you will be fine, but once you get into the outskirts it tends to get a bit more insecure.