There have been some incidents in Cayo lately, but I personally think it is still quite safe, all things considered. There's crime everywhere -- I've had two houses burglarized in North Carolina in the past year or so, in what is considered a low-crime rural area.
The number of incidents involving tourists in Cayo, a handful over the past year or year and a half, is small compared to the number of tourists who had no problem whatsoever. Most people feel entirely safe, just as they probably do back home, though in fact there is crime back home and in Cayo and everywhere.
I've been taking my family to Cayo for the past dozen years or so and I've never had any concern.