For $9 you get admission to the ROM, which is pretty good discount by itself. If you're going to this, you should definitely plan to cruise the museum with some friends for a couple hours. That guarantees a good time.
On to the party:
The main floor has a DJ and dance floor, but nobody is really dancing. Too bad because the music is pretty good.
There are lots of people just standing around the main floor. An eclectic group.
LINEUPS are the biggest downside.
Lineup recap:
1) Admission fee lineup (avoid by buying online tickets)
2) ROM dollars lineup
3) Food stand / Bar lineup
If you're planning to get food or drink, you need to stimulate the ROM's internal economy by converting to "ROM dollars".
So, if you want food or drink, buy some "ROM dollars" at the same time you buy your ticket. It will save you an extra lineup.
The bar lines, in particular, can get crazy. it's a good idea to scout out the fastest line and buy a bunch of drinks at the same time.
Food is tasty, but the portions are small, and the lineups are long. Probably not worth your time unless you're really hungry and you have friends to chat with while in line.