I'll be honest, the only thing that puts me off Voyagers is the toilet smell, which I only noticed when I was in the vestibule anyway. Apart from that the journeys I've made on one have been quite comfortable. Likewise the 180 was pleasant to travel on generally, but considering they're of a similar age the Voyagers seemed in much better condition.
Putting the interior aside, the 180 was making all sorts of rattling & grinding noises that seemed to have minimal relation to the current speed or movement from the track. They'd take you by surprise sometimes. I didn't really hear any of that on the Voyagers (or the Meridian for that matter but I suppose they're newer). It just gave the impression they weren't very well put together. The brake noise is pretty alarming but having travelled on 315s for years, it doesn't unduly concern me.
Interior-wise it seemed fine with regard to seat comfort and legroom (apart from the guy opposite me at the table sticking his legs out further than was really necessary), but what did annoy me is discovering unevenly distributed luggage racks - I boarded one coach to discover there were no racks either at the south end of the carriage I boarded, or the north end of the adjacent one, and had to get off, walk one carriage further down and get on there, to find that there were two next to each other. Really now, one at each end would make more sense wouldn't it? :P