The ROM is a great museum at anytime but transforming it into a social venue was a brilliant idea. The main floor and an area on the second floor are turned into a dance floor, each with different genres of music. The 2nd floor is generally more top 40 while the main floor is DJ'd (house/electronic) or they have a live band.
There is something fantastic about being able to wander through the exhibits with drinks while talking with friends/strangers in something other than hushed tones. The crowd is very eclectic both in age and dress and people come to have a great time. The event is never pretentious.
I love the food that is on offer but the lines for drinks are too long. They need more staff or more drink stations. Other than that, I like that it is only offered seasonally (it is something to look forward to) and don't mind that it ends early. Its a great way to start a Friday night in Fall or Spring. In particular, its a fantastic way to start Halloween. Just make sure to get your tickets early.