I've been to Les Glaceurs twice, once at the Saint-Sulpice location, and most recently the new location on University & Ste Catherine.
The red velvet I had from the Saint Sulpice location was HUGE. A bit on the sweet side though and topped with an enormous amount of frosting, it satisfied my sweet tooth (alas, the grease stains on my napkins did not). The egg nog/gingerbread cupcake from the University location was a bit on the dry side and very small. The frosting tasted overwhelmingly of alcohol (the whole egg nog thing).
The service at the University location was terrible. The girl heard me tell my boyfriend that I had tried a red velvet so she assumed I wanted one, grabbed it, dropped it, then blamed me (when I told her I didn't want a red velvet, she replied with "but you said it out loud"...no idea where her logic comes from).
a tip: if you have foursquare, upon your first check-in you get a FREE cupcake! Apparently no purchase is necessary