For cider they will be excellent. Clean and sanitize as usual for bottles. The biggest drawback when compared to glass bottles is the susceptibility to sunlight, which causes skunking. Cider generally doesn't have hops, so it's not susceptible to skunking.
I'd still keep in a dark place as usual, but other than that, they work fine for the average beer/cider providing you manage the light.
Oh, and I don't think I'd use them for extended aging, like for wines of very big beers that might sit for a year or more. That's just me, but there is probably some O2 permeability in the plastic and I'd rather only use them for stuff that I'd be drinking in a few weeks.
As far as glass goes, don't fear the bottle bombs! Study up on the process and choose a method that prevents bottle bombs. It's not hard. Unless you backsweeten your cider there shouldn't be an issue.