We came to the Maple Leafs game last year and the atmosphere was similar to that of an NHL playoff game. Of course, when these two old teams matchup, fans take the game much more seriously.
First thing I learned was how tight the lower level ushers keep the place. They don't want anyone without a 100 level ticket to venture down to the ice even for the pre-game skate. They even have curtains that they open and close from the main concourse. The concourses always seem to be packed but not because they're small, this place just holds that many fans.

Our seats in 110 were in row W which was the second to last row in the section. I loved being able to sneak to the concourse during an icing or offsides call to get a beer and was back before play had resumed. DO NOT get up to leave your seats while play is going on. It is bad hockey etiquette. Ushers won't let you go back to your seat from the concourse until play has stopped either.