I would say it's the worst I've been to for any pro sport. The only one I can remember that was comparably bad was Bell Center in Montreal. Even older stadiums/ballparks I've visited like Lambeau, Fenway, and Wrigley have better leg room than the Dome.
Habs are my favorite hockey team, hope to get up there someday. I’ve been to San Diego, Tennessee (many times home team) Astros, Oilers, Texas, Vandy, UNLV, Preds, all better room than the dome.