I haven't got one - yet. But it would be handy having bits on the leg to put your map in and scribble on, plenty of storage for pens, sunglasses etc and would stop the wife moaning about oil and stuff on my normal clothes.
My resolution for next year, though, is to procure some michelin man immersion suits for overwater legs. Yes, you look a right prat struggling into it on the apron but it would allow me to do more direct cross Channel routings (away from the rat run between Dover and Cap Gris Nez) and I'd rather look a prat than die because I wanted to preserve my (very limited)street cred.