I grew up playing hockey in the U.S., so you can imagine this visit was a bit special for me. The trophy room was spectacular, as was the collection of jerseys (Mexico?). The activity areas for kids (or us adult boys) were a lot of fun. Be a goalie... or a sharpshooter ... very cool.
It did seem to be a bit lacking on ways to learn (or teach others) about the history of the sport... and its legendary teams or players. They were a few interactive video areas, but even with modest crowds, one is left watching the selections of children who tend to press a new button every 10-15 seconds.
Thus, I enjoyed my short visit, but I would not have gotten much value out of staying longer. Perhaps this makes sense. One can find plenty of hockey history on the internet... so a kid-orientated place designed to move people along... well it certainly makes business sense. So I would suggest you plan for a 30-40 minute visit plus a walk through a gift shop at the end.
I'll always treasure the photo of me holding Lord Stanley's Cup.